31I have the infamous 2.5 that I drive daily. if you are going to try to run 31 or larger tires regear. There are formulas to figure out the proper gear selection with your automatic trans, tire size and how will you primarily use your jeep.
My favorite mod that was pretty easy and free was lowering my fuel tank and cutting the vent tube back to around 1 inch. It allows 19 gallons of fuel to be added.
Here is a link with all the info
https://wranglertjforum.com/threads/gas-tank-mod.4815/
MML is nice once you install a lift kit. I took my 1 1/4 transfer case drop out as I didn't like the look of it hanging down. The idea of lifting a jeep but lowering the TC just bothered me. the MML was easy to do and you can get them for less than 100 bucks depending on what you choose.
Headlight Mod of your choice. My friend rewired his stock sealed beam lights by adding in relays and then ran a much larger power wire from the battery to the headlights. He said it really improved. I bought Chinese LEDs, that I am happy with the output but sometimes they flicker a bit. occasionally a high beam will not come on until I flash the lights a few times. I think the worst part is for other drivers as the low beams have a very wide pattern. I get flashed a lot but I drive 25 miles from work at 1030 at night on county roads through Farm land. I meet at the most 3 or 4 on coming cars and that is rarely. The things I have avoided: coyotes, foxes, opossums, skunks, cats, bob cats, dogs, DEER, cows, donkey, owls (flying at windshield height), Lots of road derbies. Crazy rednecks that I am only guessing are on drugs in the middle of the night in the middle of no where with their shirts off. I don't stop, I just keep on going, that is none of my business LOL. So the payoff is worth it to me.
A good AT Tire, My jeep has 31" cooper AT3s and they are good but people run all types. I want to step up to 33" but I want to keep them 10.50 or 9.50 in width.
My jeep came with a 4" lift installed. It looks funny with 31" tires but the tires were brand new. A lot of people are running 2.5 lift and then adding a 1" body lift.
I guess the biggest thing is to read all you can about what you want to change. See what works for others and make your choice. I tell people that ask about buying a jeep that your not only buying a vehicle but it will be a project. until you work out all the kinks or Previous owners mods it isn't necessarily a vehicle you can just drive and not maintain.
hot and humid here in Lower Alabama, A spider shade or Alien shade help but when that sun is really beating down I put the soft top up without windows (safari style). I have soft lower and upper doors. I will put the top up and doors on without back windows and drive with the AC on and I stay very comfortable. The soft doors are another favorite mod as when a isolated storm pops up I can install those quickly. The back of my jeep has no carpet or seat. Just a pelican case.
I have Bartact seat cover in shipping right now as I hope this helps with a sweaty backside. I will have to update you in a week or so on how I like them.
Hope this helps, welcome to the angry squirrel (2.5) club!
and
keep in good maintenance and enjoy. TJ's are extremely fun to drive whether on the side of a mountain or in town. Probably the best Jeep they will ever produce. New ones are fine, but too many nannies and sensors for me. Enjoy 
