How do I optimize page structure to be selected as a source in SGE?

Short answer: Whether SGE selects your page as a source depends on extractability: each heading answers exactly one question, the answer sits in the first sentences below it, the hierarchy is clean HTML, and the content is visible server-side.

Page structure checklist

• H1 carries the topic; H2 and H3 carry literal user questions, with no decorative text between question and answer.
• Answer first, detail second: the first paragraph of every section must be quotable on its own.
• Mark up enumerable facts as lists or tables; never embed text inside images.
• Add fitting JSON-LD such as Article or FAQPage, plus consistent entity naming.
• Critical content must arrive in HTML without waiting for JavaScript; what crawlers cannot see never becomes a source.

None of this conflicts with classic SEO; the same page can appear in organic results and in AI answers alike.