It is my understanding that Google looks at:
3. H1 tag
In that order.
(Googles SEO tips also suggests using meta tags but that's a whole different discussion)
I was reading something that said you should never have more than one set of H1 tags on a page. Some themes put every separate blog post title in H1 tags so when you look at the page source there are multiple sets of H1 tags on the same page.
Anyone have any information on thoughts on this?