Be sure that the bird is 100% thawed, and dried as well as possible! Also, be careful not to buy too big of a bird. Make sure there is space enough in the pot to allow space between the outside of the bird, and the inside of pot. Otherwise you'll get a really impressive oil fountain! (don't ask me how I know)
And follow the other safety tips already given. I've only done it a couple of times because while it's fast, and if well done tastes amazing, cleanup is kind of a mess.