The advice I would give would be to not go overboard. Make your character realistic. Like, how many students at Hogwarts are registered animangi? Not that many. So that is one personality trait you should probably stray away from. I also try and make realistic names, like Jackie. Occasionally I go for something a little less common, like Rochelle (I don't know about you, but I don't here that name much) I made up my characters bloodtype and background right away, but her history kind of just formed itself.