Do your beest to keep the fingerprints and sweat off the finish by wiping down your guitar after every practice session. If you're in a particularly humid climate, keep your strings wiped down too, as they will rust before they wear out.
A moderate amount of humidity is essential for the well being of your guitar. If you live in a dry (less than 40%) climate like Nevada (Nevada is often nearly 0% humidity) or Arizona, you really, really, really need to buy a guitar humidifier. The wood of an acoustic guitar WILL shrink, crack and warp when you introduce it to a dry climate. Electric guitars suffer also, but not quite as badly. Most acoustics are built in moderately humid places like the Pacific Northwest. Tacoma Guitars Factory (Owned by Fender now) is in Tacoma, Washington and Larrivee Guitars began in Canada and now has a large factory in Southern California as well.
I own a Limited Ed. Tacoma ECM 38C (44 of 100) that sounds super fat and very well balanced. Its finish was destroyed although, by the Nevada climate. The finish separated from the body when the wood shrunk on this Pre-Fender Tacoma, and now I have a limited edition, once sweet guitar with finish peeling off of it all over the place. I used an in-case Dampit Humidifier but it didn't save this guitar. I don't know if this incident reflects more on the quality of these Pre-Fender Tacoma guitars or on the Nevada Climate. You needn't necessary purchase a room humidifier, but if you can afford it, I highly recommend that as well.
Gloss Maintenance: Clean a gloss finish instrument using either the Ken Smith Pro Formula Polish or pick up the Dunlop System 65 Guitar Maintenance Kit. It is safe to use carnauba or paste waxes on gloss instruments.
Oil or Satin Maintenance: Generally speaking, an oil finish won't need a lot of maintenance. Keep it clean by wiping it down after every use. Every once in a while you may want to polish an oil finish instrument with the Ken Smith classic wax polish. This same product is used on the fret board.