Another tip: Have a case or proper storage for EACH guitar that you own. Don't just have one carry bag for all of your guitars. When you are not playing the guitar STORE IT!! Just like anything else, leaving it out in the elements without any protection is going to damage it over long periods of time. I have 4 guitars but I generally only play one the most. The other 3 just sit there doing nothing until I need a particular sound I can't get from my main axe.. So they sit in their little baggies and hard cases until I need them (or for when I want to show them off.. hehe..).

That's not to say you should spend $100's on cases.. even if you wrap them in plastic or anything else similar to the function a soft case serves.. it's only to keep the constant weathering down to a minimum.