I need foundation, and I'd like to try the Maybelline Dream Mousse Foundation, but I'm confused about which shade to get.

Is there some secret method for figuring this out? I know I should be able to tell by looking at the package, but I get confused as to which shades are cool or warm, and how light or dark I should go. How do you pick your foundation color? (Do I just buy the three that seem closest and return the ones that don't work? I really wish drugstores had samples!)

http://www.maybelline.com/prod.....ector.aspx