Remember that a good football novel has to have the same ingredients as any other good novel: drama, convincing and interesting characters, a strong story-line, and some kind of magic in the writing.
I'm going to get hated for saying this, but honestly, fantasy is easy to write because you can do anything. It's like when Raymond Chandler brings in a bloke with a gun when he's stuck - in fantasy, up pops a wizard, and off we go.
I see genres as generating sets of rules or conventions that are only interesting when they are subverted or used to disguise the author's intent. My own way of doing this is to attempt a sort of whimsical alchemy, whereby seemingly incompatible genres are brought into unlikely partnerships.