Product pages carry the highest commercial intent on most e-commerce sites and deserve the most granular optimization attention: a unique title tag naming the specific product (not a generic template that produces near-identical titles across variants), a genuinely unique product description rather than manufacturer copy duplicated across every retailer selling the same item, and complete Product schema markup covering price, availability, and review rating where applicable.
Duplicate manufacturer descriptions are one of the most common and most damaging product page problems on e-commerce sites, since search engines can freely find the identical text on the manufacturer's own site and on every competing retailer, giving your specific page nothing distinctive to rank on. Even a few unique sentences added to a manufacturer description - fit notes, use-case guidance, a comparison to similar products in your catalog - meaningfully improves a product page's differentiation.
Handle product variants (size, color) deliberately: decide whether each variant deserves its own indexable URL with unique content, or whether variants should be represented as selectable options on a single canonical product URL. The right choice depends on whether meaningful search demand exists for variant-specific queries (searchers do sometimes search for a specific color of a specific product), but the decision should be made explicitly and applied consistently, not left to whatever the platform's default behavior happens to be.
Out-of-stock and discontinued products need a deliberate policy rather than default deletion - a 404 error on a previously well-ranking, well-linked product page wastes accumulated link equity. Consider keeping the page live with clear out-of-stock messaging and links to comparable in-stock alternatives, or a 301 redirect to the closest replacement product if the item is permanently discontinued, rather than simply removing the page.
Reviews and user-generated content on product pages provide a steady stream of unique, keyword-relevant text that the retailer did not have to write, and they double as a trust signal for both users and search engines. Encouraging and displaying genuine customer reviews directly on the product page is one of the higher-leverage, lower-effort improvements available for e-commerce product pages at any scale.