1. Get rid of the ‘alt’ tag for the avatar/gravatar.
By removing the alt tag for the avatar, you are eliminating numerous occurances of the term ‘avatar’ (or gravatar) throughout your blog. This will help eliminate overcrowding your blog posts with a term that is most likely irrelevant to the topic at hand.
2. Convert the comment Permalink anchor text to an image.
Just like the above recommendation, by removing the anchor text ‘Permalink’ from your blog, you’ll help eliminate the possibility of the word ‘Permalink’ overpowering other terms that you may be trying to rank for.
3. Use alt text for any images you use in your blog posts.
In the above two recommendations, removing potential problems is the key; however, by adding alt text to images in your blog, you are giving the search engines something extra by which to rank your site (even if it is just in the image search results).
Note: None of the above is a good substitute for good content.