Properly aged wine requires a certain environment. Here are some important things to keep in mind when storing wine:
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.
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.
Since light can also cause premature aging, store your wine in the dark.
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.
Finally, keep your wine in a horizontal position in order to keep the cork moist.