How to shift gears properly on a road bike?

A new bike shouldnt be too outa whack. No matter what gear ratio you are in, the bike should still function w/o horrible noises. Avoid the 'big to big' and 'small to small' combos. Big ring up front means you stay away from the big cogs in the back. Same with 'small'. A chain slipping off is a sign of a serious problem and you should get your dealer to look at it.