If you need to store your guitar for any length of time, take the following advice into consideration. First, detune all strings by a whole step, otherwise the neck may pull forward if temperatures change too rapidly. Be sure the instrument is cleaned and polished, then place it into its original case along with a small bag of silica, which will absorb any excess moisture. Finally, put the guitar and case in a large plastic bag (the black trash bags will work, but you'll probably need two). Now place it in a cool, relatively dry place such as a closet or under your bed. Never place it in an attic, an unfinished basement, garage, or so forth, where temperatures will almost certainly fluctuate.