Make Sure the Champagne is Cold
Start off by chilling the bottle. The best serving temperature is around 45° Fahrenheit, that would be about 7° Celsius. If you put your hand on the bottle it should feel very cold not just cool.

A good method for making sure you get the right temperature is to fill your ice bucket, or any deep container if you don't have a special one for wines, and let the bottle sit for 15 to 20 minutes. Adding just a bit of water to the ice in the bucket will actually help cool down your bubbly. There's an explanation based on physics and heat transference, but all you really need to know is that it works.

It's important to have a chilled liquid. Champagne that is too warm will foam and spill when you uncork the bottle. You'll lose some of the bubbly and make a mess. Of course, it also tastes much better at the right temperature! You don't want to make it too cold though, or you'll lose some of the flavor of the wine.