Using a glitch found in the Helpful Glitches page, you can gain basically infinite free exp and gold (until level 30)
Preforming the glitch
To start, open SFH 3 and go to the custom game tab. Make a custom game with 5 bots, difficulty level of your choice, and with 15 capture ctf. Once spawned with your squad, (you will need more than 2 heroes) commit suicide and select to respawn as another character, but do not select change hero. The game will now automatically play itself and you can have infinite gold and exp!