H1 for main titles use only one per page / similar or identical to meta tag. (example; title of book)

H2 for core sections / use secondary keywords (chapter titles)

H3 for subsections (subsection with in the chapters)

paragraph 1: Answers the main search immediately in the first sentence. keep it short under 50 words. Keep all paragraphs short. under 5 sentences and use primary keyword within the first 100 words.

paragraph 2: Expands on paragraph 1 the why and how

H4 hyper-specific details or supporting bullet points beneath H3

Paragraph 3

Monospace for code or data only