Welcome!
Either Scarsman's or Schwaartzy's for skid plates, the OEM are ok from what I've read but aren't the sturdiest though you can get reinforcing plates from 4speedfunk (thorparts.com) to beef them up. I made my own UCP from some 1.5"x1" 1/8 tube (came from a truck rack), it's sturdy enough that I can lift the entire H3 without it deflecting.
Rock sliders are a must as well, OEM is good if you come across a pair, otherwise Schwaartzy's like you're looking at. Some people like Rocky Road's as well, but I don't think it's mounts are as sturdy as they should be.
285's are a great choice if you're doing mild offroading/crawling, and spend most of your time on the street. I have 33" Duratracs which are a popular choice, but there are other good options as well.