Be sure that you have all your navigational links to the rest of the site also in here for the search engines to follow. Once your inner page information is within this tag, it's as if your site is not framed at all as far as the search engines are concerned, because now they can read everything and index your site properly. Of course, doing all this is only useful if the information in your main page is well-written and utilizes your keyword phrases properly. The above information takes care of your front page. However, there are other issues having to do with getting the rest of your pages indexed properly when you use a framed site.
Most Web designers use frames for ease of navigation.
That is, they have a left-hand frame with a static navigational bar or buttons that never change. When someone clicks on a button on the left, the frame to the right brings up the new page accordingly. Because of this type of design, there are usually no navigational links on any of the inner, framed pages. But if you do, and someone searching in the engines finds them, they will be what I call orphaned pages. Savvy Internet users might look at the URL and try finding the root directory, but most users don't have a clue about doing that.