Run and hope he doesn't see you
Take out your sniper if you brought one and take him down
Try your best to take him out with an assault rifle
Run in zig-zags so he has trouble picking you off
Dont panic and spray and pray
Call in back up to help you guys out
Take cover and pop up once in a while for a headshot
Have a teammate stay back with a sniper (mile away) picking them off froma distance while you do the strategy above
Each player zoom his scope in on a door to watch for trouble
Go prone. Play dead.
F*** death im doing this for all of us. Just stand there and have faith.
Throw a smoke grenade at the floor and go prone.
A tactical one
A semi tactical one
A prepared one
A rushing one
Here's an interesting quiz for you.