Temperature is key! It should be cool and constant. Is 55 degrees some sort of magic temperature? No. If your wine is colder it will age slower; if it's warmer then it'll age quicker. It should probably never be cooler than the 40s or warmer than in the 60s. If there's a seasonal variation that's not too bad. If the day-to-night temp of the wine storage area varies than you've got a problem. A basement is fine, a wine fridge is best, but can be costly. If nothing else use an interior closet floor. The last thing you want is a wine rack sitting on the kitchen counter. Styrofoam shippers might be bad for the environment, but they're good for your wine.
There should be no direct sunlight. Moderate humidity is needed. Too low and the corks dry out, too high and you get mold on them.
Store bottles so the cork stays wet (there is wine in contact with it). This means laying the bottles on their side.
So even if you just have a few bottles you're not drinking immediately store them in a cool, dark place on their side.
|A really bad idea|
Keep an updated inventory of what you have. There's the CellarTracker.com website for cellar management and review or create your own spreadsheet. You should know what you have and what you should be drinking now. Nothing like having to say, "Oh hell, where did that '09 Chardonnay come from?"
If your wine hobby is really out of hand you may want to keep receipts and get your wine insured.