Welcome to the group.
Honestly, my vote would be to basically leave it mostly stock. Do whatever maintenance and repair is appropriate for the age, mileage, and condition of the vehicle, but upgrade a few things, then just enjoy it. Modifying the truck is a slippery slope and, frankly, there's not much for upgrades out there. It's a great truck as-is; goal number one is just getting—and keeping—it, on the road.
If anything:
Invest in a proper lift and suspension package: Old Man Emu springs, shocks, and struts. Great reputation, great ride and handling qualities, moderate lift. Pricey, but worth it. I wouldn't bother with spacers here, unless it's to help level out your stance...if you'll already be taking everything off the truck, just replace it the right stuff.
Get some quality all-terrain tires in OE size (P265/70-15), or maybe upgrade to LT's or 31x10.5 if you think you'll have an inkling to venture off-road one day.
If you like the stock look but want larger wheels (yours are 15x7), consider finding (or piece together) a set of 17x8 LE wheels from 01-04 Pathfinders or the 17x8 "Supercharger" wheels from 02-04 Frontiers/Xterras. Good looks without having to fuss with backspacing and center bore nuisances.
If you're into tunes, upgrade the head-unit and/or speakers; maybe add an amp and sub.
Anything else is going to requiring drilling, more wiring, and perhaps even custom fabrication. Not that I frown on that stuff, but if you're just getting into things and hoping for bolt-on stuff, you probably won't find it. I wouldn't go gonzo with a bunch of stuff you're probably not going to use, unless that's just part of the dream you're going for. I won't judge.
If you plan to be in the vehicle for long trips, focus on maintenance, creature comforts, and roadside readiness, especially if you have passengers. Perhaps consider making some sort of storage/cargo unit for the rear to help keep gear and tools organized and accessible; add a reliable air compressor (I love having an on-board system, personally); or purchase a 12v fridge/freezer for those extended road trips (may require some other things, like a backup battery or fridge slide, etc.).