My first purchase for my 2011 JK was the ACE Rock Sliders (ACE JK Rock Sliders (2 Door)
). They look really nice, provide good protection and second as a step.
If you have a hard top, I'd suggest looking into a bikini/summer top for the summer (that's next on my list). If you don't want to go as far as a bikini/summer top, you can get an emergency top for under $100 for quick coverage in case of a downpour.
If you plan on offroading I suggest upgrading tires/wheels and possibly getting a lift. I'd also suggest getting a sway bar disconnect (also on my list).
It wouldn't be a bad idea to upgrade your radio deck to a marine/water proof deck. I've already gone through one deck due to rain. I've also upgraded some speakers to waterproof speakers.
If you plan on taking off your doors a lot, you may want to relocate your mirrors off the doors and onto the Jeep (Lange Originals 023-110 - Lange Originals Quick Mirror II for 07-12 Jeep® Wrangler & Wrangler Unlimited JK - Quadratec
Those are just a few ideas I have yet to do/have done for my new Jeep, hope it helps.