Any serious guitarist respects his instrument as something very high in value to him. He does not treat it as a toy that is thrown around and left lying around if it is slightly inconvenient for him to put it way. What entails taking care of your guitar in the proper way? Well, let me tell you!
I always like to keep my instrument well taken care of. I'm even a little hesitant to let other people play in fear they may accidently chuck it across the room or set it on fire. Well, maybe not but I definitely don't want them to drop it and knick it.
I'll start with the first thing you should do, even before you pick up your guitar. Wash your hands. I'm serious here. The oil from your hands not only corrodes the strings but it shortest the life of the guitar neck (the wood). You're also going to want to wipe the guitar strings down when you are done playing to remove any dirt or oil from your hands that was left on the guitar when you played. This will greatly increase the lifespan of your strings, which is recommended to be changed about once a month but will always differ depending on how often you play and how clean you keep your hands and the strings
Keep you guitar in an environment that will be free of constant temperature and humidity change. That means don't keep it in your garage because it clutters up your room, as it can warp and damage your guitar.
Every time I change my strings I like to wipe it down with a nice coat of wax that I bought at a guitar center. This will help keep it clean and will also give it a nice shine to show off its beauty. It will also give it a semi protective coat.
If you're looking to keep all the scratches off your guitar I'd suggest investing in a back guard. When you stand up and play the back of the guitar rubs all over what you are wearing, and if you're wearing a metal belt buckle that could result in some nasty gouges on the back of your guitar.
Considering guitars can be very expensive, that would be most unfortunate.
It can also be good every once in a while to put some type of oil on your fret board when you're changing your strings. I've seen some older guitars with dry dry fret wood, and it isn't a pretty sight. Try to keep it moisturized with a lemon oil to keep it from becoming rough or even worse, cracking.
Other than keeping all the nuts and bolts snuggly tightened, that about does it for basic guitar maintenance! Keep those guitars in good shape so they can keep on a blazin'.