1,300 hours and I'm still bad. I try to play one team death match before playing in what I call real games. I also find playing squads as opposed to Duos gets me more kills per game. Good luck!
I found that spending about 10min at the 200m shooting range + 3-5 aim target popup rounds in the training map wake me up and then I do 2 TDMs to practise on alive targets.
Many people would feel this to be too little of a warmup still.