Never go B pistol round.

If you press LMB (or whatever your fire button is bound to) while looking at the enemy, they will almost always die. If they don't you done fucked up.

Always have a good lurker, someone more reliable working under pressure and wielding a rifle. Everyone is valuable to the team but always send your most consistent player to lurk, he can turn the tables of any round as long as he places his shots correctly and moves to the right places at the right time.
An example is when rushing B, have a lurker stay around the T spawn area to pick off people rotating from cat and long while informing the team at B if they are coming from CT mid.

Invite me to your game.