There's not too much that can jump up and bite in Moab so if some of y'all don't get around to armoring up the bottom, you won't be in dire conditions. I only hit my skid once the last time I went and that was because I decided to take a really bad line. Now I'm not saying forgo all the skids, but don't worry if you're not covered fore to aft -- especially on the Easy trails. Radiator and engine skid will suffice if that's all you have on right now.
I do recommend sliders though, highly recommend them. I banged my NXRocks sliders around a lot.
Make sure your CB works well. Or at least make sure you're on the right channel that day. Oops.
If you're a Gen 2 person, a spare ABS line wouldn't hurt as there's always at least one snapped one -- or learn how to fix one using speaker wire.
If you're a manual driver, adjust your parking brake if it feels loose. That can make some obstacles a lot easier than having to worry about slipping cause it's not holding.
Just make sure your ride is in great operating condition. Think about it, you have to trek there, wheel for a week, then trek back home. You don't want small little things to ruin your trip. So whatever makes sense to you to do -- fluids, brakes, tires.
There's auto parts stores in town as well as tire stores. Moab4x4 Outpost is a pretty solid off road shop and I recommend them because they helped me out, gratis, the first year I went so I could get on the trails.
Oh, and if you like to drink (not in an alcoholic sort of way) bring plenty of beer. Utah alcohol laws suck. After a long on the trails, everyone pretty much collects in either the condos or campgrounds and have a few beers to unwind. So bring the good stuff and share. Caveat, don't bring too much that if you get pulled over, you'd be in deep poo poo.