Properly aged wine requires a certain environment. Here are some important things to keep in mind when storing wine:

Temperature:
The ideal temperature is 55 degrees Fahrenheit; however, 50-60 degrees is a good range, and 45-65 is okay. The temperature should remain fairly constant to prevent premature aging.

Humidity:
A medium-high humidity is best - around 70% or in the range of 50-80%. Any higher than that can damage the label, and any lower can dry out the cork.

Light:
Since light can also cause premature aging, store your wine in the dark.

Ventilation:
Ventilation is important in order to avoid strange aromas from affecting your wine. Be aware of strong odours near your stored wine that are unpleasant.

Position:
Finally, keep your wine in a horizontal position in order to keep the cork moist.