H1 should be highly relevant to on page content and meta title.
Use H2 and H3 for content sub-headings
Use H4, H5, H6 for secondary content (sidebars, footer, etc.)
Bold & Italics When writing content that spans multiple paragraphs, heading and sub-headings help give structure to the document. Bold and italicized words call attention to the reader. They are also used by search engines as a guide. Use bold [ <strong></strong> ] for most important keywords.
White Space Good use of white space (empty space) brings readers attention to your content.