New 98 xj what do I need to know?

First post, was wanting to know what everyone's suggestion for what to repair or replace first. I plan on draining all the fluid, but what else do I need to look at? ???

It's a 98 xj, 4.0 motor, 4x4, 4dr, auto. Some rust on the frame but not terrible. When in 4x4 hi it "creaks" some when turning sharpish. I'm guessing u joints?

Amy suggestions are appreciated!

first you should take inventory of whats worn because I cant see your XJ over the interwebs.

all fluids should definitely be replaced to be on the safe side.
fix any leaks
check for worn or loose suspension bushings, tie rod ends, balljoints.

if you are asking what to upgrade first, then i'd suggest
1. fender trimming
2. frame stiffeners
3. rock rails
4. lift kit
5. and whatever matches your preferences