Action Replay Codes

Enter them at the cheat enter menu:

(M)
U2FT-B7KV-U32PE
679Z-Y392-VJZTP
RA0M-8CTY-XKQ8Y
0HYV-5QQW-16DXN
E9FZ-A3QA-YCERP
D4F8-2JXT-JG522
PJWJ-NUDZ-3N1FR

Infinite Ammo
RY1R-10MB-F6FE9
FTJT-E6E4-N6JFR
C8YB-Q7AU-7E0EU

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.