you have to cut off limbs... so aim for legs first to drop them then arms... usually one leg and one arm kills anything.
Look for green boxes on the floor and stomp them to get ammo/supplies. Also, look for boxes or lockers with white lights (as opposed to red) to open them for ammo/supplies.
imo, the gun you get in the begining is the best... but to be honest I never "pimped out" any other weapon.
I thought the story was better than most...
