Start the China mission and complete the first objective for $30,000. When you have completed the objective, quit and reload the mission to get another $30,000 (to get the money you may have to walk back down the mountain). You can repeat this as many times as you want.
When you are in 'Campaign' mode and you want to switch character go to the 'Campaign' menu and select 'Start New Campaign' followed by the character you want to play as. Then return to the 'Campaign' menu when you now choose 'Continue Campaign' you will start with the character you selected.
Get a sniper and start a new game on china. Go and destroy the bridge and get to the air boat and get past that part and get to check point and end game start over and you should have money and be able to do it again. Its that easy!!!
You can also unlock the following achievements when completing the campaign mode with the professional difficulty. Complete level 1. 30G Complete level 2. 30G Complete level 3. 15G Complete level 4. 15G Complete level 5. 15G Complete level 6. 15G
Unlock all secondary weapons and all special weaponsAdded 21 Mar 2008, ID #2309
If you are able to complete the game in professional difficulty you will unlock all the secondary and special weapons. Pro difficulty is unlocked after you have completed the game in either recruit or contractor difficulty
Unlock all primary weaponsAdded 21 Mar 2008, ID #2308
After you have completed the game in either recruit or contractor difficulty all primary weapons will become unlocked when you play through the game again. It also unlocks the professional difficulty mode.
There is a little trick with which you can accumulate quite a bit of cash, you just have to be prepared to do the same thing over and over again... Ok, here is the deal.
In China, complete the taasks at the beginning of the level, blow up the bridge and get to the hovercraft. Here the game will auto save your money. Now quit out of the game, reload and go back and do it again... And again... And again... Well as many times as you want.