Heat is the number one enemy for wine. Temperatures higher than 70F will age a wine more quickly than is usually desired.
The ideal temperature range is between 45F and 65F (55F is often referred to as perfect).
But Not Too Cool
Keeping wines in your refrigerator is fine for up to a couple of months, but it's not a good idea for the long term. The lack of moisture in the average fridge could eventually dry out corks, which would allow air to seep in and damage the wine. Also, don't keep your wine where it could freeze (unheated garage in the winter). Freezing could expand enough to push the cork out.
Steady As She Goes
Avoid rapid, extreme or frequent temperature swings. On top of cooked flavours, the expansion and contraction of the liquid inside the bottle might push the cork out or cause seepage. Aim for consistency.
Turn The Lights Off
Light can pose a potential problem for long-term storage. The sun's UV rays can degrade and prematurely age wine. Ever wonder why vintners use coloured bottles? It's like sunglasses for wine.
Don't Sweat The Humidity
Wines should be stored at an ideal humity of 70 percent. The theory goes that dry air will dry out the corks, which would let air into the bottle and spoil the wine. Yes, this does happen, but unless you live in a desert or in arctic conditions, it probably won't happen to you. Anywhere between 50% to 80% humidity is considered safe.
See Things Sideways
Bottles should be stored on their sides in order to keep the liquid up against the cork, which theoretically should keep the cork from drying out. Horizontal racking is a space-efficient way to store your bottles, and it definately can't harm your wine.
Where Should I Keep My Bottles?
If you don't have a cool, not-too-damp basement that can double as a cellar, you can improvise with some simple racks in a safe place. Rule out the kitchen, laundry room or furnace room, where hot temperatures could potentially damage your wines. Alternatively, you could purchase a wine cooler from a local reputable company.