Summarize the following:
Before you're ready to serve it, keep your champagne (and all wine) in cool-but-not-cold conditions with little direct light and very little variation in temperature. Basements that stay between 40ºF and 60ºF (4ºC-15ºC) are perfect. Horizontal storage helps prevent the wine from spoiling and allows the cork to remain moist, which will help keep the air out and keep the gas in. This is an important factor in maintaining the flavor and bubbles in your champagne. Colder champagne tastes better, but it is also less likely to bubble over when you open it. The ideal drinking temperature is between 45ºF and 48ºF (7ºC-9ºC). If you've got the time, 4 hours or more in a refrigerator will be enough to put your champagne into the proper range. The classic way to chill champagne is in an ice bucket. Champagne buckets are frequently larger than other wine chilling buckets to allow for more water and ice. You should fill the bucket with half water and half ice and let it chill for 15-20 minutes before serving.

Summary:
Store the champagne in a cool place. Store the champagne horizontally. Chill the champagne before serving.