Be aware that crouching in CS:GO has no impact on rifle aiming at all. There is no improvement on recoil, or the time it takes to recover from recoil. You can test this by shooting rapidly at a wall, crouched, and standing. Though it is a good tactic to suddenly crouch, when your enemy is about to shoot, simply because they may be aiming at your head, and miss. But, on the flip side, they could be aiming at your chest, and then get a head shot. Some guns, such as the desert eagle, are better when crouching. Again, you can test this when standing or crouching.
In addition to SimonL said, you can also do a few more things. I have found that with the headshot crosshairs, holding the gun at head level, and doing death match headshot only rounds, along with the suggestions that Simon made, I have increased my headshots to about 60-80% of my death match kills. I used to maybe get 20%.
- Use the training_aim_csgo Map
- Play Death Match Headshot Only Rounds
- Pick a Good Crosshair
Use the training_aim_csgo Map
Go to the work shop, and download the "training_aim_csgo" map. To do that, click "Play", then "Find a Game", and you'll see a "Workshop" tab. You can start the map by typing "map workshop" and using your arrow keys to pick the map. You will need to use "noclip" in the console, to get out of the pit. Then, just hit a gun on the wall with your knife, or another gun, to change guns. Then hit options on the other wall the same way, to change your practise settings.
Always exit the game after using this map, as it messes a few things up, and prevents your user interface from working if you go into a lobby, for example.
Play Death Match Headshot Only Rounds
Play lots of Death Match, with a Desert Eagle only. Go for single shot headshots. The deagle does not do well, when rapid firing, unless at point blank range, so you'll need to learn the recovery time.
Pick a Good Crosshair
Picking a good crosshair, that works for you, is very important. Some people like a single dot, some people like a crosshair like a plus sign. Personally, I figured out how to create a "Headshot Box". You put the person's head in a box, and pull the trigger. I find it is a very good visual cue for my brain to shoot. My current cross hair is below. You can put this in a text file called ch-box.cfg, under C:\Program Files (x86)\Steam\steamapps\common\Counter-Strike Global Offensive\csgo\cfg. Make sure the file doesn't end in '.txt' or you won't be able to use it from in the game. After that, I bind a key to execute it by running the following in console.
bind o "exec ch-box"
The ch-box.cfg file is below...