[mupha]

Use regular links within the body of your content, thoey will be the most effective, particularly if you link with the keywords relevant to the target page. Depending on your blog setup (and as you mention Trackbacks I'm assuming it's a blog), the trackback links may be nofollowed anyway, which leaves them useless - though may be able to can change that with plugins.

Interlinking between from new content to old content is important as it helps to encourage googlebot to keep visiting and indexing your older pages. Some kind of "Related posts" plugin can help interlink automatically.