On-page SEO for product pages
Product pages don't compete for broad terms - your collection pages do that (next lesson). Product pages win specific searches: "anine linen shirt navy," "wool overshirt herringbone men." Low volume per query, but the intent is nearly a wallet-out. On-page work for products is about being unambiguous about exactly what the product is.
The title tag: the highest-leverage line
The title tag (what shows in the search result, defaulting to your product title in most themes) should read like the search you want to win: product name, key attributes, brand. "Anine Linen Shirt - Navy | Yourbrand" works because someone searching those words sees their words reflected back. The two classic failures are the same as product titles generally - the poetic mystery name with no category noun, and the keyword pile-up. If your product names are strong, title tags mostly take care of themselves; that's a data convention (Phase 2), not a per-page chore.
The description: unique or invisible
Here's the uncomfortable economics of product descriptions: if you paste the supplier's text, you're publishing the same content as every other stockist - and Google keeps one copy, usually the biggest site's. Unique descriptions aren't an SEO nicety; they're the entry fee for being indexed at all (as the previous lesson's "crawled - currently not indexed" verdict shows).
What makes a description work for search is the same thing that makes it work for customers: covering what buyers actually want to know. Material and how it feels, fit and how it runs, care, styling. Every real question answered in the page is a long-tail query the page can now match. Structure helps both audiences - a fit note under a fit heading is scannable for humans and parseable for machines.
The attribute layer, again
Rendered attributes - material, fit, dimensions from your metafields (Phase 1's theme lesson) - give the page precise, machine-readable relevance that prose can't fully deliver. Plus valid Product schema for the rich result (price, stock, stars in the listing). Two products can rank identically and the one with stars and price takes the click.
Images and the rest
Descriptive file names and alt text ("navy-linen-shirt-collar-detail.jpg", alt: "Navy linen shirt, collar detail") - accessibility, image search, and AI readability in one habit. Internal links in the description where natural ("pairs with our linen trousers") pass relevance both ways.
The honest summary: on-page SEO for products is 80% product data quality wearing its public clothes. Stores that did Phase 2 properly find this lesson mostly done.