I agree with all what spoogob said (Polish a lot, get feedback, etc.) except for one thing: Once the game is up for bidding you cannot sit back and wait for the bids. You need to promote it, contact sponsors, maybe make a game trailer, whatever you can to make them bid. Once they place a bid, you have to push them to get a better offer. If a month passes and you don't get decent bids, you are doing something wrong.
If you want advice to sell your game, go to FGL forums, there are a lot of threads there that will help you to find a sponsor. I'm market level 7 there, and I still look for advice from more experienced developers. Most of them are willing to share their wisdom.