Maybe you have wondered about which is your dominant eye and if you should shoot with the cue under it. Some people say you should, while others say the cue should be under your chin, in the center of your face. Here is an article from BD writer Tony Robles that will help you find where you should be sighting the cue. Not everyone is the same, so it's important to find out what works for you. Try this exercise as it will help you quantify objectively, where you should be "sighting" the cue.
http://www.billiardsdigest.com/showinstruction.php?id=2
http://www.billiardsdigest.com/showinstruction.php?id=2