Careful with this one, an S4 is by no means a tiny controller and it can be a pain in the arse to fit it into a booth along with the rest of the gear.
My best advice is to check out the booth a few nights before you play there, the size is the biggest problem, ensure you have ample room. Dont rock up 10 mins before your set and start complaining that you need more room, you'll look like a dick.
also, this is a very important one; DO NOT rest your controller on top of any other gear without some form of protection/padding/etc. You dont wanna be the guy who bent the tonearm on one of the decks and fucked up the night for the rest of the DJ's.
Other than that, take backups. CD's, Vinyl & USB if you have them. You never know what you'll be faced with when you eventually get up behind the decks, but you need to be able to keep the party rockin no matter what. What happens if some bitch pours beer on your laptop because you didnt have her fave song? After humiliating her and getting her kicked out, you need a backup plan.