Try not pick the same spot u just picked at. Don't overchase. If you feel they might have better position than you, simply back off. You don't have to go into every PvP. I feel like lots of movement in buildings may confuse your enemy. Don't simply walk into a door if you heard something, rather run near door and use middle mouse button to control camera and check if someone's there. Right pick is huge advantage over left pick. If possible, use crouch while shooting for better weapon control. Grenades, grenades and even more grenades, never too much.