I don't tow often, but one thing I do is "check often". Like, after 20-30 minutes (or miles), check everything. chains still attached, lights still working, no tires or hubs getting hot? Whenever I stop I do a quick check, make sure nothing has changed.
Something I've gotten bit by a couple times is potholes and uneven ground. It becomes very easy to drag the hitch. For a while I carried around some cut up 2x's so that I could level off if I needed to (if I was towing an RV I might have a stack already, being the cheapskate that I am).
Also, whenever I back up my trailer and manage to have a spotter, I tell them "if you can't see me in the mirror then I can't see you". It might be helpful to work out some hand commands so that all are on the same page.
Something I have only recently had a chance to use is a backup camera. I bought a cheapo one to go onto my rearview mirror for my truck, as it has such lousy rearwards visibility--but thought ahead and bought a camera to put onto my enclosed trailer, so I could see what was behind me. And wired it up so that I could easily switch between the two. For what it cost, and the work to install, it seems like a cheap way to make things better when you have to back up solo.
Edit: I tow rarely, so I'd take the above with a grain of salt.