Use the radio commands quickly to communicate efficiently. And don't hesitate to respond to them if you hear them. Switch to lighter weapons to run. This is great if you need to move or dodge quickly. Watch the Crouching Be careful when you duck down for that acuracy shot because those who dont duck usually keep there crosshair at waist level.
Most people also aim for the biggest part on there oppenents body.
It, always being the shoulders to the waist. Or if you are battling it out with another player standing up, dont duck your sure to get shot in the head. When jumping to make yourself a harder target, crouch as well. One player should crouch and the other one should jump on top of him. If you need to get even higher, the player above can jump and the player below should let go of his crouch key.