If you aren't too mechanically inclined to crawl around & look at stuff on your own (which is fine BTW) I'd recommend finding a mechanic that you can trust either through personal recommendations or reviews. Pay them to do a thorough inspection (usually around an hour of labor) to test drive it, put it up on a lift, and give you a full write-up on what needs attention soon and what will need attention later. When you're talking about a 15 year old vehicle with 200k+ miles failures of any sort are to be expected, be it major or minor. It can be tough sometimes to find someone you can trust that won't pencil whip up a list of deficiencies looking for a payday, but they're out there. When you do find one hold on to him. You might check local Jeep clubs in your area also to see if there are solid technicians around you.
TJs have common weak points like the cooling system, the crank position sensor, and the ignition switch/actuator, but that doesn't mean something else won't go wrong either. I wouldn't worry about it stranding you on the side of the road, but as vehicles get older stuff breaks. The best way to figure out what you need is to get a set of eyes on it that knows what they're looking at.