How do I get used to using a mouse and keyboard instead of a controller?

If you can't turn in a circle with your mouse, your sensitivity is too low. Crank it up until you can do a 360 comfortably without lifting it and repositioning. I have no idea why this advice suddenly became "lower the sensitivity and just use your whole arm across your whole desk" but, that shit sucks. Especially if you don't have room.
It's a good idea to disable acceleration and, when possible, use RAW input for the mouse so it moves 1:1 with your hand. You can do this in most competitive heavy games, and you might want to also disable acceleration (mouse smoothing) in Windows' own settings.
- Accuracy. When the slightest twitch makes me spin its way harder to consistently hit targets, especially small ones at a distance. Slower is better for sniping, faster works if you're rocking shotties. A buddy of mine plays so much quake he has macros that adjust his mouse speed upon switching weapons so it adjusts accordingly, and it really makes a huge difference.
  
  Logitech mx518 is the best gaming mouse ive ever used. I originally got it for $30 on a sale in like 2009 or so when i built my second main gaming pc. Then in 2020 when i got back into PC gaming and built a new rig I just checked to see if it was still available as my old one the cord had gotten chewed, and i guess they rereleased it and i ended up paying like $70 but i still think it was worth it. Anyway moral of the story aside from awesome ergonomics it has a little dpi switcher above and below the mouse wheel that lets you cycle tne DPI and therefore the sensitivity super quick and on the fly.
- lower the sensitivity and just use your whole arm across your whole desk”
  Carpal tunnel avoidance
- Thank you, I will try adjusting the sensitivity and playing around with it a bit. I'm not using Windows so I don't know If I have mouse smoothing enabled. I'll look into that. I'm with you on the desk space. I don't have alot of it.
- I have no idea why this advice suddenly became "lower the sensitivity and just use your whole arm across your whole desk"
  Because that's how you get the greatest level of precision.
  
  Not really. Long time ago I was used to a mouse with ~3000 dpi and after a few years I was extremely precise with it. Also faster, obviously.

There's no real secret other than to just play games and get used to it. FPS may or may not be the best choice for this. You could also play other games like strategy or city builders instead.
My sensitivity is so if I drag my mouse straight to either side, I'll do about 7 or 8 full spins by the time I get to the end of my mat.
- Thats crazy how much the preferences differ. I do like 2 spins with my big ass mousepad.
  
  From left to right i do a 180 lol depends what kind of games you play
  
  I don't like to have to do that swing move that streamers and other hardcore gamers use. I like to use as little arm movement as possible

For the most part, it's just like how you learned to be good with a controller: experience. The more you use the mouse the better you get. You brain just learns that this amount of movements equals roughly this distance moved on the screen.
For a lot of people, disabling mouse acceleration helps with precision. By default there's an acceleration curve, so you move the mouse faster and the cursor goes even faster, disabling it makes it so the cursor tracks the mouse precisely. It can make it harder to do a 360 though, as acceleration can help get the speed needed. Dial in your sensitivity settings to where it feels comfortable for aiming, because if you make the sensitivity too much for the 360 it'll be really hard to aim with any sort of accuracy.
There's a rhythm game called Osu! if you want to stress test your mouse accuracy.

This is how M+KB natives feel on controller.
You will get used to it if you keep playing, but it might never feel natural unless you use it exclusively for a while.
I'm a trackball + keyboard user so mouse + kb and controller both feel sort of almost right but somehow wrong to me
Also some genres lend themselves better to one or the other. I prefer controller for platformers and fighters, but prefer TB + KB for almost everything else
- Trackball gang! There's dozens of us. Dozens!
  
  Your numbers are growing! I've met one of you in the wild 10 years ago!
- Also some genres lend themselves better to one or the other. I prefer controller for platformers and fighters, but prefer TB + KB for almost everything else
  Yeah, I agree. I use a controller for platformers, fighting games and racing games. Also sometimes action RPGs- I've played Dark Souls with both input methods.
  My only absolutely hard line is using a controller for any kind of shooter. I just can't, and trying is a very frustrating experience.

This question fills me with sorrow.
- Sorry, was not my intent.

There are 3 way you can be better at aiming with a mouse:
Disable acceleration (enhanced pointer precision)
Lower your sensitivity
Use a lighter mouse
Past that, it's practice, practice and more practice. If you only recently moved over to M+KB, you haven't developed the muscle memory. Start with games that just require you to click on things, like Civ games or Stardew Valley, and games that don't require rapid movements, like Portal.

Turn off mouse acceleration in windows, it's called enhance pointer accuracy or something stupid. Set your mouse DPI to 400 or 800 in its software and get a decent sized mouse pad, Adjust your in game sensitivity to the point a natural arc of your arm does a full 180. After that it's all practice

I can understand where you're coming from. As a lifelong PC gamer, it took me ages to adapt to controller usage (I use a controller on PC for some game types now) and I still can't play any sort of shooter with a controller.
It'll inevitably take time. You're shifting from existing muscle memory, to an attempt to develop an entirely different kind of muscle memory. I'd suggest trying to use a PC for as many tasks as possible, even for stuff you usually use your phone for. Even general PC usage will help your muscle memory to develop.
Don't give up, you'll get there eventually!
- I use a controller on PC for some game types now
  I'll use a controller if I'm emulating a console game(obviously.) The only PC games I use a controller for is strictly driving a vehicle in GTA5 and Cyberpunk, or racing games. WASD isn't pressure sensitive, and it does my head in trying to feather the throttle to take a corner, or creep past an enemy so my companion can shoot them from the window. Just makes more sense to use a controller for that. Also too broke to buy a decent wheel and pedal setup.
  
  I can definitely relate, similar experiences were my initial reason for getting a controller for myself. I ended up becoming a controller geek, though. Right now, I have a PS3 DualShock clone, a Logitech controller with DualShock ergonomics but Xbox face buttons, and then I have retro controllers for Sega Genesis and the SNES. Looking to expand beyond that eventually but virtually any game type works flawlessly with that setup haha
- I use a mouse and keyboard for everything except gaming. I hate using my phone. I use to play basic keyboard and mouse games when I was a kid but it's been a very long time. I actually started my game tonight and after adjusting my mouse sensitivity it's easier than I thought. Hitting left shift with my pinkey to run kind of sucks but oh well. Still slightly cumbersome but I think I can get used to it. I'd still rather use a controller if given the option but I think I can manage. Thanks!
  
  Get a good mouse with some extra buttons and it makes the whole experience a lot nicer. And remember you can usually change any keybindings you dont like. My mouse has two extea thumb buttons and theres some games where ill use one for sprint or dash, although left shift feels pretty natural after you get used to it for a while. The biggest difference with mouse is turning like you said, its not like a conteoller where you can just hold it to the side and then release to 'reset'. Regardless of your preferred sensitivity tou have to get used to 'resetting' the mouse yourself by pucking it up and recentering it. But once you get used to that it feels way more responsive and accurate than controller aiming imo. I got a steamdeck a couple years ago and its largely replaced my pc for gaming but theres still times where i wish i had a mouse, even with the touchpads.
  
  There's no shame in getting a good USB controller for your games. I'm hardcore PCMR but I have no issue with PC players using a controller. The fact that you actually have those options is an excellent example of why PC is so awesome.

Practice/getting used to it
Also since you are learning try low sensitivity + moving your arm instead of high sensitivity + wrist movements

Play a less demanding single player game to get used to the mouse. I'm not sure how it handles mouse and keyboard, but I'm thinking something like Ratchet and Clank.
- I'm actually trying an indie horror game called DreadOut: Keepers of the Dark because my controller won't work for some reason. I have been reccommended Ratchet and Clank: Rift Apart before. Maybe it's a sign to play the game.
  
  I would strongly recommend that a single player RPG would be the best. My first mouse and keyboard games were fallout New Vegas ultimate edition and fallout 3 of the year edition. I would recommend if you buy either of those. They are wonderful games and very easy to mod.
  
  Playing a horror might not be the best to start with.
  Edit: Third person view in some games might be really awkward with mouse and keyboard. Especially older games can be clunky af.
  
  They're all great. If you can get your hands on the originals, they hold up well. But don't play the remake of 1 from a few years ago.

No matter what sensitivity my mouse is set to I seem to get stuck when turning. On a controller I can turn completely in a circle, but not with a mouse unless i’m missing something.
are you using running in circles as a benchmark? as a one continuous loop that is not going to happen with a mouse unless you have infinite desk and arm lengh. Generally mouse users do circles in segments: turn a bit, move mouse back to center and repeat as nescessary.
If you've mostly used controlles, yea, m+kb is going to feel unnatural. Same applies in reverse too. Different worlds - it can take quite some time to get familiar with the other.

Practice

Practice
- Always solid advice. Thy will be done.

Are you using mouse only? On my controller I usually use both analog sticks to move and turn the screen at the same time which allows quick rotation if necessary. Same applies imho to mouse and keyboard. I use the mouse to turn the screen and wasd to turn my character which at least for me leads to the same result.

There's aim trainer games to practice mouse speed and accuracy.
edit: aimlabs on steam.

So with mice, you have a center position you return to after every move. From that position, ideally you should be able to turn your character between 270°- 180° degrees with a single swipe.
You'll want to use a mouse with an at least 1000 hz polling rate. They can be found online for less than $30. There are websites to test polling rates.
I recommend a DPI of 800. 1200± DPI will often make your sensitivity way to high, even if you lower the in game sensitivity. 400 DPI has more hitches.
Turn off mouse acceleration in windows.
Make sure the sensor in the mouse and the mouse pad is clean.
Lighting round: light weight mice are preferred. 8000hz is better that 1000hz polling, but not by much and uses a lot of CPU usage and requires correct USB support. Don't aim at the enemy, aim where they are going to be. Warming up a bit does help your aim. You don't need to spend a lot of money to get the best gear or to have fun.
Useful mouse comparisons. https://www.rtings.com/
There is a mouse pad compare website, but I can't find it.

Practice

Everything they said but first start by playing some solitare first, it was included in early windows to teach mouse skills
- No play Balatro
  
  I played that too. Good shit.
- I'm actually pretty good at Solitare. It's fun.

A lot of comments missing this part: you have to lift your mouse to relocate it back to center. A low sensitivity mouse results in so called "rowing".
There are a lot of different preferred styles, as an example: eSports tends to higher DPI (dots per ich) since every millisecond counts but the precision falls behind which can be trained.
After all I would recommend trying a mainstream shooter game like Counter-Strike and leave the settings vanilla.
Start a match or training or what else and pick yourself 3-4 points of the environment like a corner of a wall, a bench and so on.
Now aim at one point, close your eyes and try to move your cross hair onto another point, open your eyes and you will notice that you are either too far beyond the aimed point or didn't reach it. This offset can be adjusted inside the most in-game setting by decreasing or increasing the mouse sensitivity.
If you always have to crank up or down your sensitivity in every game to the same direction you probably should change your mouse DPI. Most mice come with software where you can adjust this. Also when playing on windows disable mouse acceleration.
- There are a lot of different preferred styles, as an example: eSports tends to higher DPI (dots per ich) since every millisecond counts but the precision falls behind which can be trained.
  This is accurate, yeah. Sometimes pros use 400 DPI, some use 1000 DPI. There's probably at least a few madlads using 2000+ dpi or some shit.
  Personally, I use 1600. I don't have a particular reason for that- I might actually try turning it down- it's just what feels comfortable.
  
  Woah, I just checked and I also use 1600 DPI. Let's start a cult.

While it's true that experience is the only way to 'get used to' something, having the right settings can minimize the effort of it. It should almost be as effortless as pointing at something with your finger.
You will have to go into the settings and adjust your sensitivity to what matches your personal proprioception. The best way I know to do this is to open up the game and then pick a point to look/aim at (if it's a first-person/OTS third person) or a point on the screen to put your cursor if it's something with a static camera. Place your mouse/reticle on that point. Then swing it out for a loop/heart/star shape and try to snap your view right back to the same point based on where it would feel natural. Don't readjust to get there if it's not at the spot, just note where you are actually aiming compared to the target. If you go past it, sensitivity or acceleration is too high. If you don't get there, it's too low. If you are off to either side on a perpendicular line, (e.g. you come from straight to the side and end up too high or low) that's you, and that will just have to come with experience. .

Disable mouse acceleration in the OS and in the game
Enable raw input
Decide on a grip for your mouse, your options are claw, palm, or tip. Which type of mouse you have will kind of dictate that choice for you at some level
Download CS GO and an aim practice map
Adjust the sensitivity until you start hitting shots semi-regularly. You should be able to do at least a 360 on a single mouse pad, some people prefer a higher sensitivity. You'll have to decide between using more wrist or more elbow.
Memorize the DPI and in-game sensitivity you used, use it for mouse-sensitivity.com and try playing a very different game from CSGO with those settings.
Odds are the best settings for CSGO will be less sensitive than the best settings for open world RPGs, ultimately it's your call and depends on the games you play, but once you have a setting, stick to it for a few different games, then adjust as needed.

Try to keep the mouse centered in your mousing area. The aiming motions for the mouse are shorter, snappier throws rather than the long and slow arcs of an analog stick.
So move the mouse to your aimpoint, then pick up and recenter. I find that a full "flick" for me should go about 360 degrees. You can also check for mouse acceleration settings, this increases the rotation of your view based on how fast you move the mouse. Good for games where action is coming in from all sides, but it can cause some problems with precision and consistency.

Aimlabs will help. Free on steam last time I checked.
- Thanks, I'll check it out.

With a mouse you turn back.

There's no point... You'll be back on controller once the carpal tunnel sets in lol
- I thought it was funny 🤷‍♂️