Infinite XP and Gold Glitch
Before finishing a side quest that doesn't trigger a cutscene, draw your weapon. Once your weapon is drawn, talk to the NPC that completes the quest. Once your character puts his or her weapon away, repeatedly hit A till desired level or gold amount is reached.
Infinite points in Armor
This can be done with Aveline or Warrior Hawke at any point in the game. All you have to do is equip, un-equip, and then re-equip a shield. Do it as many times as you want till you max it out.
Item Dupe and Money
Place your most expensive item into your trash alone. Go to a merchant, select sell and go to the trash tab. Hit Y and immediately press A. If you were successful the item you sold will have sold twice giving you extra money. To duplicate potions you must purchase two or more than do the above cheat. Enter into buy mode and buy back all but one of the item you wish to duplicate. Repeat the cheat and your stackable item should have increased for as many as you have sold.