During Game Play Go to Menu Options then Cheats and enter the Codes below:
Good guns to take on any mission are the AK-47,MAC,GAT,9mm, M4,silenced pistol, and Bulldog.
Save your money. If you do, it will pay off for you in later missions when all the better weapons are available. Money is also needed to get better special moves (where popcorn is in the theater) and the meds from doc when needed. You should buy all ten painkiller bottles.
Grab your opponent and interrogate him until he drops a credit card or his wallet. Then, execute him and choose to steal. He will either give you a credit card or wallet, depending on what you got the first time. Normally when you kill an enemy and steal from them, you will only get either a wallet or a credit card, and never both. Use a close range head shot to get $5,000 or more in credit cards or money, jewelry, and armor depending whether you need it or not.
When you are low on health and have no armor, when you take out an enemy out, steal from them by pressing Square by the body. Most of the time they will drop some used armor for you.