Work through it in order. Fixing checkout before you trust your analytics just moves the guesswork later.
Measurement
Verify purchase tracking, deduplicate events, confirm funnel steps fire, and segment by device. Without clean data, everything after this is opinion.
Mobile experience
Under 2.5s largest contentful paint on 4G, tap targets above 44px, sticky add-to-cart, no layout shift.
Homepage and collection
Clear category entry points, filters that match how people shop, and social proof above the fold.
Product page
Outcome-led copy, image depth, visible reviews, delivery and returns clarity, confident CTA.
Cart
Shipping estimate, threshold progress, easy quantity edits, no forced upsell interruptions.
Checkout
Guest checkout, express wallets, minimum fields, trust cues, and error messages that explain the fix.
Post-purchase
Order confirmation, delivery updates, review request, replenishment prompt. Retention is the cheapest conversion you will ever buy.