Alright I'm just going to give you guys a very simple and effective method of improving your intuitive aim in both of these games. Using a rifle or pistol in a deathmatch server will dramatically increase your ability to perform flicks to the head, will teach you to fully understand the spraying pattern of a rifle, how to correctly pre-aim around corners and will work hard on your muscle memory. What you'll want to do is find a good deathmatch server on either GO or CSS (dust2dm is pretty popular) and perform these routines:

Counter-Strike: Source

Kit 1:
M4a1
USP
Do 50 frags with this kit, but make sure to use your usp like for a good 20-25 consecutive frags

Kit 2:
Ak-47
Deagle

Again 50 frags, get that deagle down real well. After 100 frags, you may go for the AWP for however many kills as you like, although i wouldnt practice an awp on most d2dm server where the awps are camping. What you wanna do is be able to be volatile and always moving around as if you had a rifle (run around with deagle out, take awp out for long range). Iceworld DM is a small popular deathmatch map which has very simple corners and awping there will help.


Counter-Strike Global Offensive

Kit 1:
m4a1
p250

Kit 2:
ak-47
glock

Same deal. Don't wear yourself out in a deathmatch server going above 200 frags. Dazed publicly said at one point that it's much better to use deathmatch in small doses rather than one large dose. A version of this aim workout with less frags, just warming each of those weapons up real fast is very efficient to get you warmed up for competitive play. Hope this helps !