I have been guilty of this in the past, when creating the style sheet, I would make my own header tags (such as .header1 or .sub2). The problem with this is that the fake-headers do not carry as much weight as the <h1> to <h6> tags.
So instead of using your own headers and subheads, create or edit the CSS the same way for the <h1> to <h6> tags as you would for your own creations. Make them look the way YOU want them to, and by using the PROPER tags, it will carry MORE weight for the content between them.


