First go to the cheat menu and press R2,R1,L1,L2,left,down,right,up, square and all cheats should come up. Chose either the DEAD EYE cheat to give you more power, RICOCHET ALL cheat to shoot a lot of enemys in one shot as the bullet bounces off each guy nearby, or BIG HEAD cheat to give you a better head shot ability. At the beggining, you have to defend the tank repair dude, right! Well, right when you begin, go around the tank into an opening in the wall. Then go into this one building straight ahead. Then you will see Health and PPSH ammo. You will not need the ammo, but you will need the Health in your inventory. There will be 1 more Health thing in another room and alot of PPSH ammo. Then when the infantry dudes come zip out, press -> on the direction pad to accquire your DPM. Use that. It is much better. Then mount inside the tank and if you see a group of soldiers or a machine gunner or tank, press L1 and R1. If you see a single panzersheck (rocket dudes) use R2. Leave the gun dudes alone. Hope this was helpful!