The supposed ideal upkeep would be to wipe down your strings, fretboard, and finish after every use. This will definitely improve the life of your strings. But really all of it's prolly not totally necessary, and I only wipe the finish occasionally. But I'll especially give it a thorough cleaning when changing strings (when you can access the headstock and near the nut, near the bridge, and the fretboard). That's considering general home use though...up on stage, in a basement, or wherever playing for hours and sweating all over it, yeah, that's a different story. Clean it.

I've always used Martin guitar polish. It's not real expensive, and does a good job. And, I've been playing since '94, and I think I've only had to buy like 3 bottles so far...it doesn't take a lot, thus it will last awhile. You could also use naptha, most commonly found in lighter fluid. Obviously you'll also need a soft rag of some kind (I've always used cotton bandannas).
You might get a differing opinion, but Dan Erlewine (highly regarded guitar tech) strongly emphasizes not to use lemon oil, thus most furniture polishes. The oil may work it's way into the wood and lift the finish. At the same time, I'll mention he strays away from guitar polishes, going for naptha or just a plain rag...but he deals a lot with practically priceless vintage instruments with thinner finishes. Polish should be ok on newer ones.
You might've seen guitar humidifiers, but being that you live in Texas, I seriously doubt you need one. I'm not sure where abouts exactly you are, but unless it's the far western and southern arid parts, our relative humidity hardly ever drops below 45%.

I seriously recommend you buy the book Guitar Player Repair Guide (by Dan mentioned above), not only for this topic, but also almost any other issues that can arise. Actually I'd consider it a mandatory read for any owner of guitars. Set-up, repairs, mods, upkeep, you name it...it's a "bible" so to speak.