Congratulations on obtaining the Cherokee. What sort of overall condition is it in? Good condition XJ's in original configuration are increasing in value quickly. If yours is in this category please resist the urge to make modifications that can't be easily undone. The more that its original the more value it will have in the long run.

The items to address is nearly endless but here are some areas to start with:
* Drain as much old gas from the tank as you can.
* Look around the engine bay for critters that may have moved in. Look for debris on top of the intake and exhaust manifolds that can burn, check inside the air cleaner box, etc. Look for signs of chewed wiring.
* Look for cracked vacuum hoses and fittings. One that often breaks is at the rear of the valve cover. Certain vacuum leaks can result in engine performance problems.
* Check and plan to replace the rear hard brake lines. They seem to rust quickly and that is a safety issue. A long line runs from the engine bay along the driver side frame rail to the rear. From the distribution block on the rear axle there is a hard line that runs to each side. Check the flex lines for cracking while you are at it. Passenger side front hard line is also prone to rust.
* While underneath check for significant rust. If repairable the sooner you address it the better. Initial problem areas are along the rocker panels behind the front tires, front passenger side floor approximately above exhaust, and rear wheel housing behind the rear tires, gas tank mounts.
* Check condition of brakes. Include a brake fluid flush as part of fluid changes you are planning.
* Check the distributor cap and rotor. They are an easy replacement if there are signs of residue or arcing
* Spark plugs are easy replacement
* Consider doing an engine oil analysis. This will give you some idea on the mechanical condition of the engine.