In a great discussion about content relevance, this SEOMOZ article outlines what the author believes are the optimal placements of the primary keyword phrase:

  • In the title tag once, and possibly twice (or as a variation) if it makes sense and sounds good (subjective, but necessary)
  • Once in the H1 header tag of the page
  • At least 3X in the body copy on the page (sometimes a few more times if there’s a lot of text content)
  • At least once in bold
  • At least once in the alt tag of an image
  • Once in the URL
  • At least once (sometimes 2X when it makes sense) in the meta description tag
  • Generally not in link anchor text on the page itself (this is a bit more complex – see this post for details) source

It it hotly debated if the H1 or the H2 tag is more relevant; many pundits on SEOMOZ will claim the H2 tag is more important, at least with Google.