Last time I was at the Jeep Service Garage, I noticed on the big price board that they charge $59 to rotate tires and lubricate steering and suspension components. Your manual says to grease the steering linkage every 3000 miles and to grease the suspension ball joints every 6000 miles. There are many other grease fittings you may have from aftermarket mods like greasable universals, sway-bar disconnects, and shackles for YJ owners. However, this will only cover the stock TJ grease fittings. I understand that the stock YJ has quite a few more than this.

If you don't already have one, you can get a grease gun at Amazon for $18. Grease tube refills are cheap. The manual specifies NLGI Automotive Wheel Bearing and Chassis Lubricant Type GC-LB. All grease refill tubes will have this National Lubricating Grease Institute rating on the packaging and/or tube itself.

There are seven zircs in all. Here are the locations of the zircs.

Upper yoke-to-steering knuckle balljoints (On both sides)

Lower yoke-to-steering knuckle balljoints (On both sides)

Drag link to tie-rod joint

Pitman arm to drag link joint (left)
Frame to track bar joint (right)

I find the best time to do this is while waiting for the oil pan to drain. While you're at it, this is a great time to lube your door, windshield, tailgate and hood hinges. This should be done periodically to reduce and prevent squeaking and the inevitable rust.