title_body: How should one store liquors in a home bar?
upvoted_answer: Some tips:
  
  
  Protect your bottles from sunlight and extreme temperatures. 
  If your bottles have cork tops, make sure to keep the corks moist so that they don't disintegrate (just turning the bottles upside down every month or so for a few seconds does wonders). 
  As the level in each bottle drops, consider transferring the contents to a smaller bottle. This prevents volatiles from leaving the liquid and also excludes oxygen from the bottle (though whether you're mixing in extra oxygen during the transfer is perhaps a worry). If you know beforehand that you will take your time on a certain bottle, I'd rebottle it at the outset.
  If you already own it for wine (or are otherwise serious about keeping half-empty bottles for a long time), you could also use something like an inert gas wine preserver (e.g. PrivatE PreservE or Winesave PRO) to add a layer of what is basically Argon over the liquid. I haven't tried this.
  
  
  Vermouths and other alcohols ~20% ABV don't keep well for long once opened. Treat them like wine: drink them faster or open fewer of them. They will lose their aromas, then oxidize, and finally turn to vinegar.
  
  Liqueurs with low water activity (read: lots of sugar) will probably stay safe to consume for quite a long time (years), but they are still prone to oxidization leading to off flavors. Re-bottle at the outset if you must, or consume faster, or discard and buy new.
  
  Consider storing your bitters in the fridge.