For an overnight I'd be finding something very safe to put my money in (I used to have a coat with one pocket unpicked so it fell right down in the lining, and velcro on a small bag or pouch is good too), making sure my security buddy knew exactly where I was and what time I would be leaving, and obviously doublechecking that the punter is actually at the address he's claiming to be.
I would also want some assurance that nobody else could access the place, but that's a difficult one as obviously he's hardly going to say if a group of mates are going to turn up (which is one of the many reasons I don't visit private residences). Don't park your car where it can be seen, and all the obvious stuff like don't accept food or a drink unless you've seen it unsealed and opened first.
I've never taken deposits (once, I think when a flight was involved), but you can do that too if there's time? If you can sleep then fine but even if you can't that doesn't mean you have to put up with being mauled about all night; I never got any sleep on overnights, and I haven't done them for years.
Edit: cross posted with Flo