Welcome to TYF.
If your truck came with an owners manual, there are maintenance and service intervals listed in it that are based on mileage.
Check the normal stuff such as air filter, oil, and spark plug condition. Spark plugs in particular have a 100K mile replacement interval, so I'd buy OEM replacements and get them swapped out. Use AC Delco iridium plugs, as they are OEM and yield the best results. Also have a look at the serpentine belt (check it for fraying/cracks). Personally, I also check and replace all fluids (brakes, power steering, front and rear diff, t-case, trans, engine oil, pretty much everything but engine coolant unless it's due) regardless of mileage when I buy a used car, as part of a maintenance baseline. This way I know that everything is fresh and taken care of right off the bat, and if I find any issues I can nip them in the bud before they become big problems. YMMV, that's just my personal preference.
As for what you can do yourself, that's a purely subjective thing based on your mechanical ability, comfort level, and tool selection. Seaching the forum will yield alot of how-to stuff (check the tech section), and YouTube is a great resource for the DIY crowd - you can generally find how-to videos for pretty much everything. Good luck!
