When I bought my Jeep it came with a new Centech wiring harness. I have read a alot of threads on this forum, and I've especially noted all of the electrical problems a lot, and I mean a lot
of guys here have had. I am happy to say with the new wiring harness, plus all of the dedicated ground wires I ran, I've only had wiring problems I've created myself, which have been few. I think new wiring will save you a lot of headaches down the road, especially with some research on here. I'd start with these:
Anything by Jeephammer is great. John Strenk also knows alot about wiring.