Start by reading every word at
http://jd.offroadtb.com/Then all the Build Threads here.
Then define the kind of terrain you want to travel on, your budget (you can spend $400-8000 or anything in between), time frame, and experience level. Are you going to offroad for the first time in your TB and want to gain experience along the way to enhance safety, or are you an experienced offroader just trying to duplicate the performance and capability of some previous vehicle you've wheeled? What's your tolerance for risk, what kind of weekend or week-long trips do you intend, and so forth.
We can't give you much advice until you "define your mission" as I always say.
Click on my build thread (link in my signature), and you'll see an Envoy that I can live out of for a week at a time, on pretty much the harshest terrain outside of what full-blown rock crawlers go on, for 200-400 mile stages unsupported by civilization. Is that your goal?
Think about terrain and mission, then that helps you define the size and type of tire, then that defines the size of lift and wheel spacers you might need. Then you have to budget for and equip yourself with survival gear, extraction equipment, spare parts and fluids, etc., etc. Or if you want to go to offroad parks or trails for weekends only, and never live out of the vehicle for a week, that's a different mission shared by a lot of members here, probably most of them.
Welcome, and have a great time reading. You found the right forum for seriously offroading GMT360s.