Always maintain your crosshair high,aim it in the head of your teamate and maintain its position so when you will encounter an enemy its an instant headshot...
Practice your Spraying or Rapid Shooting of AK47/M4A1 using a "BullsEye SPRAY Design".
* Aim your Crosshair in the "BullsEye Spray design"
* Try to Rapid/Spray your Ak47/M4a1 in the "BULLSEYE SPRAY". ( by holding the left click of the mouse, hold it until the 30 bullets runs out)
* Look at your BULLSEYE SPRAY.. if there's no bullet outside the Bullseye Spray.. then your damn good.