A road atlas and/or maps are the most essential items, and know how to use them. Don't leave home without them. Know how to use your rig. Bring a pair of rubber gloves for handling the sewer hookups, and a spray bottle full of bleach/water to clean off the water spigot before you hook your water to the campground's water hookup. If hooked up to a sewer hookup, leave the black water tank valve CLOSED until just before you want to disconnect. Then open the valve and empty your tank. (This will save the possibility of a major jam. We had to learn this one the hard way.)
The national forest campgrounds rarely have hookups. Most of them have pit toilets, and water spigots every few feet. Only a few campgrounds in state parks and national parks have them, either, though Yellowstone has Fishing Bridge RV Park (if you're lucky enough to land a spot there). If you want full hookups, all of the RV parks in Sturgis have them. You just have to pay more for the site, which makes sense, because somebody had to bring that power, water and sewer in and it wasn't free.
DOnna