naughty dog made it easier to get lots of headshots. tee hee.
2. play gold rush a lot. be a team player, revive teammates ASAP.
toss the treasure as much as possible. you can have teammates draw fire while you take the treasure to the treasure chest.
3. get an extra grenade before a battle. trust me.
4. melee attacks, 2 hits equal a kill, a sneak melee is an instant kill.
5. stay with your teammates.

be a team player and you'll get lots of cash.

don't worry too much about levels now. all that cash is gone when the real servers get switched on October 13th.