Readable permalinks
Under Settings → Permalinks, choose “Post name” so URLs describe the content.
One clear H1 per page
Use the page title as the H1 and organise the rest with H2 and H3 headings in order.
Sitemaps
WordPress generates a sitemap at /wp-sitemap.xml. Submit it in Google Search Console.
Descriptive alt text
Describe what an image shows. It helps accessibility and image search.