The use of subheads is a great way to break up large bodies of content online, however, make the subheads useful. Think of your reader scanning the page, looking for the specific piece of content he or she is interested in. Help them find that information with informative, useful subheads.
Remember, not everyone will read the whole page. Many will scan down, looking for one particular piece of content. When writing for the web, help people find it with strong subheads.