1. Mouse sensitivity
The first advice I might give you is make your sensitivity to be comfortable to make flickshots. Also your hand must be warm before you play CS:GO no matter if it's Deathmatch or Competetive.
2. Practice, practice and practice again.
Secondly, your skill will improve as you practice, if you want to become a professional player, the secret is practice! Train and improve your AWP skills vs bots or in real matches, but make bots move! And one more thing, you can make bots use walls, so you can train your reflexes.
3. Play Deathmatch
Third and last, but not least, play DM and if you want to be an aggressive AWP player, you have to adapt to not staying in one position, if you prefer playing passively, then you need patient! I know it's hard, but just camp on DM. Play at least 30 mins every day with the AWP.