Header tags set sizes but each browser interprets that size (and margin) differently. It's very annoying.
I use header tags as a way to organize concepts (or words) in an outline format. Like this:
H1. Main Subject
H2. Sub Topic
H3. Idea
H3. Idea
H2. Sub Topic
H3. Idea
H4. Detail in Minutia
H3. Idea
Don't know if that's right though.
