Easy kills
Have a rifleman, sniper, and a demo or support. Use your sniper when the threat indicator indicates that there are men from afar (yellow). Use your rifleman when it turns orange, and your support or demo when it turns red.

Medals
Bronze Star: Get 15 kills.
Silver Star: Get 20 kills.
Distinguished Service Cross: Get 25 kills.
Congressional Medal Of Honor: Get 30 kills.
Purple Heart: Get wounded or killed in action.