Do not underestimate the fucking riot shield
Marathon, Lightweight, and throwing knife and you will be pissing people off all game
When you see an enemy and you both start shooting at eachother, hit the prone button right away and you become a MUCH smaller target to hit and your accuracy goes up
Pay attention to your allies locations, if your ally has a spray setup follow them at a distance with an AR, if your ally is a sniper stay close to them with a spray setup incase of flanking, if your ally has an LMG he's a fucking noob unless he's got a silencer on it