Featured snippets reward content that's structured to directly and concisely answer a specific question, more than content that's simply comprehensive.
Answer the Question in the First Sentence
State the direct answer immediately, then expand with supporting detail afterward, rather than building up to the answer gradually.
Use the Format the Query Implies
A "how to" query favors numbered steps, a comparison favors a table, and a definitional query favors a short paragraph.
Keep the Answer Self-Contained
The snippet-worthy portion of your content should make sense on its own, since it may be shown without the surrounding context.
Next step: Use the Get Source Code of Webpage to see exactly how a currently featured page has structured its answer.