ARMY OF TWO

Man of Many Masks  - 50 G 

Purchase every mask variant.

If I Were a Rich Man  - 40 G 

Earn one million dollars in total over the course of campaign mode.

Money Glitch

This cheat of earning quick cash will enable you to become a millionaire without the need to complete the entire game three times.

Complete the game up to the 5th Mission (China). Make sure you have enough money to buy a Stinger or an RPG. I found the Stinger easier, but at $42,500, it might be a little expensive for some at the beginning.

Start the China Mission (any difficulty) and your first objective will be to blow up a bridge with a convoy passing over. This objective is worth $30,000. 

Use the Stinger or RPG to shoot the middle of the bridge to blow it up. Then run down the hill, back to the Hovercraft. Make sure the checkpoint triggers. You will know when, in the upper left of your screen, a HUD appears with “Checkpoint” and “Total Cash“  Once the money has been credited, quit your game. If you quit before the checkpoint, the money will not be credited.

There are two maps that are available for free download through the Xbox Live Marketplace. The one map included is a campaign add on of an alternate ending for the final mission Miami. This map can be selected even if you have not beaten a single mission. 

When you play through this mission at the very end on recruit it is possible to kill the final boss Dalton in under a minute. If you put your partner into aggressive mode and focus all fire on him disregarding the other enemies. After beating him you will get 75,000 and the game will end. Simply return to the game menu and select start from checkpoint to begin at the start of the final battle to repeat as many times as necessary. I managed to get over 500,000 in about 15 minutes.