You will also want to get a free catalog from 4wd.com and quadratec.com
A lot of people bedline the interior floor. I would just use one that isn't very thick [texture wise] so that it doesn't hold in dirt. Duplicolor makes a spray-can bedliner that is pretty popular, but you will need a lot to do the whole interior tub.
And take a look at Rubicon Express lift kits if you haven't purchased one yet. They are affordable and durable.
You will want to upgrade your wheels and tires soon. Since you have a YJ, I would stick with aftermarket 15" steel wheels for several reasons. They are CHEAP. If you happen to destroy one offroad or hitting a big pothole, you can toss it and buy a new one. And tires for 15" wheels are also cheap.
You're probably itching to get some good off-road bumpers as well. You don't have to spend a fortune to get a good bumper. While Smittybilt does get knocked a lot for poor quality, their SRC bumpers are pretty good for the money.
Front Smittybilt Part 76740D - SRC Classic Rock Crawler Front Bumper with D-rings
Rear bumper with tire carrier Smittybilt Part 76651D - Classic Rock Crawler Rear/Tire Carrier Bumper with D-rings
If you're waiting to buy bumpers, 4wd.com runs specials about every other month where they sell bumper packages. The package includes front and rear bumpers with free rock rails. This can save you some money if you're willing to wait for the special.
And the best advice I can give you is to read read and read some more. There are thousands of posts in the General forum and YJ forum to help you fix, maintain and upgrade your Jeep. As with any vehicles, the more you read, the more you learn