How do you practise?

Aim maps never really worked for me. I use map exec's for nade practice and learning areas to prefire and good vantage points (as I AWP most of the time, kinda shit with anything besides the AWP, decent with AK though).
Besides map exec's, I just practice in deathmatch honestly. It's a little more fast paced and you are playing with all skill levels from "I got the game 2 minutes ago" to Global Elite.