Within an article-oriented page (such as a blog post), the element (level 1 heading) is commonly used to markup either:
On your blog's home page, I would use H1 to denote the site title and H2 for the titles of the individual blog posts that are published on the front page.
When entering a particular article, though, I would use H1 for the article title and an anchor for the site title.
This is a nice and semantic setup that will also be appreciated by Google when it crawls your site.