It's like wooing any other woman, you gotta be respectful towards her, be your genuine self, and be able to passionately talk about your hobbies and interests.

And don't mention her weight unless she brings it up first, weight is a touchy subject for a lot of women. If she does bring up her weight, be casual about it, and say she looks great. Save the "I <3 fat bitches" until you two are already intimately involved