I had two come to mind. One is removing the grill and placing a screen on the backside. The screen can be bought at home depot or lowes and attaches with zip ties and zip tie anchors on the back side of the grill.
The other would be removing the carpet and herculining the floor of the tub if you can live without carpet. This would be great if you plan to run topless alot. It would make cleaning the interior easier as well as easier to drain water when it gets wet. The kit runs about $100.
There are threads detailing both processes if you are interested.
Edit: Forgot another important easy one. I've seen a ton of posts about rust on the undercarriage. You could get some POR15 and coat the undercarriage just to be safe. Shouldn't cost too much either.
2012 JKU Rubicon, 6 spd, 4.10, AEV 2.5", Duratrac 315/70/17, Level 8 Tracker 17x8.5, Teraflex HD hinge and carrier, JCR Dagger shorty prerunner, ACE rock rails