Shyans - I was in your position 3 years ago or so, and with the forum's help and a lot of searches I now am able to do all of my own maintenance. As mberry said, a service manual is really nice to have, especially for quickly referencing torque specs for various parts. I suggest printing up all of the relevant torque specs on a piece of paper and leaving it in your garage - so when it comes time to torque your drain plug, you can just check the sheet quickly.
You can VERY easily change fuel filters. All you need is a bottle/container to catch the fuel as you drain the housing (by pulling the yellow lever), and then simply unscrew the filter cap(a big 1 1/8" socket I believe), remove the filter, discard the o-ring. Then just reverse the process (coat the o-ring with a little motor oil). No need to torque it down super tight, just a half turn or so past hand tight. Turn the key to the on position and wait for the lift pump to prime/fill the cannister - and you're done. This process I believe is outlined in the owner's manual. Fleetguard stratapore is the preferred fuel filter.
Oil changes are simple, and no different from any other vehicle. Get a filter socket to attach to your ratchet/long extension from walmart or geno's garage. A strap wrench will also work well if you can reach the filter with it. Preferred filter is the fleetguard stratapore 16035. Geno's garage, or your local cummins dealer will have them.
Very easy is changing the diff fluids. You will definitely already have the tools you need. Simply unbolt the pumpkins and let the fluid drain, clean them out and rebolt using the awesome stock reusable gasket, and then refill. 75w90 GL-5 fluid, with the option of using 75-140 in the rear if you really tow heavy.
Above all the easiest is changing the transfer case fluid. Simply pull the drain plug and allow it to drain. Close the plug and open the fill plug - fill and close - done. Use ATF +4.
For the diffs and transfer case fluid - I highly suggest getting one of the diff fluid pumps they sell at most auto parts stores. Now I'm not talking about the $10 fluid transfer pump, I'm talking about the $6 diff fluid pump, which actually threads onto most standard size bottles. It's great because one end threads onto the cap of whatever fluid you're pumping, and the other end has a long hose that you can put right into the fill plug of wahtever you're filling. Makes for infinitely less mess than trying to use a funnel at that angle and pour. I also use it for pumping 2 cycle oil into my jetski without spilling it, as well as doing the diff fluids on my ATV's, which are at almost an impossible angle for a funnel. . As far as tools go, it's hard to better spend $6.
I hope this helps , as I know it's really rewarding to do my own maintenance and I think you'll feel the same way!
Attention: TDR Forum Junkies 
. I wanted to convert it back to a two car garage, but wifey says no way. 
