What have you learned the hard way when it comes to cellaring?
Cellaring should have a few simple rules. Predominantly, store wines in a cool place with no direct sunlight, and as even a temperature as you can get. Do not cellar just one bottle of a wine under cork because there is a fair chance it will be off, or not as good as it should be, when it is opened. When I was a lot younger and thought I knew everything, but I broke a number of these rules and paid for it with wines that I kept too long.