Page elements and keywords

[freehits]

The idea of including each page's target keywords in an even format throughout the page and in natural uses has been kicked around. I am curious to get some insight on which elements this includes, and which dont seem so important.
The title tag and h1 is obvious, and I like to have it in the first h2 tag. Also variations in a second h2 tag,and not further down the headings than that, only variations in the h3's. The body text I keep at about 3-8% depending on what is natural sounding to the reader. This leaves comment tags which i tend to use after any <hr>'s or at the start of a table and include target words in there as well. The footer text? the footer links? image alts? image file name?



These elements and others, which are the essential part parts thought of as 'needed areas' to contain the keyphrase when seeking to spread it throughout the page? and which are pointless overkill just adding to pagesize?