Most people understand that you must keep your wine safe — in a cool, humid place with no vibrations or wild temperature swings. Fewer understand that your spirits also need some TLC.
Consider beer. Beer often comes in dark brown or green bottles because the glass blocks the ultraviolet radiation that can break down the beer and turn it into a skunky mess. So, store your beer in a dark place.
Spirits also need some love. The rules are somewhat similar — keep them out of direct sunlight, avoid temperature swings. Keep spirits tightly corked to avoid evaporation; an opened bottle of most spirits will keep for a very long time, but opening them to air will cause gradual changes until you are left with a nasty-smelling sludge. Some spririts can handle being kept in a decanter (e.g., Brandy and Benedictine) whereas others will change character (e.g., some Scotches).
An ideal solution is a dark cabinet away from heat sources, keeping spirits in their original bottle and maintaining the bottles’ seals.