What I have found to be the best way for me to earn gold is through trading. I will buy an item for a price lower then I know I can sell it for. Then resell it for higher then I bought it for, but lower then anyone else. Normally this is a trade to pick up once you have around 10,000g or so. That way you can pick up several items. Normally tend to stick to Contribution items though. They tend to sell better then the Event Items. =)