Most amateurs (myself included) seem to lose distance in three ways that are kind of related:open clubface, poor swingplane maintenance, and a narrow takeaway. When I learned to widen my takeaway and deliver the club back along the same path, I saw some real gains in my distance.

:Note: I'm not a PGA pro. These are really just my observations. Golfgiva, Ringer, or JCGolfpro could give some better advice, I'm sure.