The best ways to find promo codes and discounts is to search the internet for as many websites as possible that offer promo codes and discounts. Such as bestfares.com
Sometimes the actual airline website will also have codes. So try american airlines.com. Also if you go to sites like travelocity.com you can also find many discounts there as well. And if you are a member of some organizations, you can also get more discounts, such as triple aaa or enterntainment. I know if you are a member of entertainment.com you get 10 percent on your american airline purchase. And last but not least, look for last minute deals flights, sometimes you can find great deals with them as well, thanks.