Some of what I'd like to see:
Don't redo the origin. Batman should be an already established hero maybe in his first year or two as Batman.
Use some of the more fantastical villains like Mr. Freeze, Poison Ivy, the shapeshifting Clayface or Man-Bat to distinguish it from the Nolanverse's more realistic villains. Or use Penguin and the Riddler.
Stay away from Schumacher camp but don't make it was dark as the Nolan films.