How can you get fast levels in combat arms

if you want to level up faster i would say the fastest way is to buy a MINIMI and play on cabin fever. use your default with an attached scope for far away zombies and spray with the MINIMI in close range. Ive gotten up to a 14 multi-kill streak using the MINIMI and it doesn't take a lot of skill. using a 100%-exp upgrade i got almost 500 exp in one game.