If you have several guitars, it’s worthwhile to know a few basic practical tips about how to store them properly, especially if it’s for a few months or more.
The first and most basic rule is to store your guitars in their cases, standing up—not lying down with one case on top of another. When storing several guitars, the cases should look like suits on a rack rather than a giant deck of cards (see photos). If standing them up isn’t an option, store your guitars (in their cases) on their sides, with the upper side pointing up.
Second, keep the string tension on the neck, but loosen the strings one or two half steps. They don’t need regular tension when in storage, but having no string tension at all can lead to neck bowing problems.
Third, if possible, store your guitars in a room or a closet nearer to the center of the building rather than near an outside wall. This helps maintain a constant temperature and is especially helpful if you live in an area that experiences climatic extremes. A case humidifier is a good idea during dry winter months.
Fourth, store vibrato-equipped guitars with the arms detached (the lone exception here being Bigsby® vibratos, which can be folded back to rest below the top of the bridge, which is the highest point on the guitar).