A list of thirty UX rules with no priority isn't advice, it's a checklist for feeling busy. Some of these change revenue. Several are repeated because they've always been repeated.
Search this topic and you'll find lists of thirty rules. Use whitespace. Make CTAs prominent. Optimize for mobile. Reduce friction.
Every item is true. None of them are ranked, none carry evidence, and "reduce friction" is advice in the same way "score more points" is a sports strategy.
The useful version answers two questions the lists skip. Which of these actually changes revenue, and how would you know on your own store rather than in general?
The ones that reliably matter
These show up over and over in audits, and when they get fixed the numbers move.
The price is visible without scrolling, on a phone. Sounds too basic to list. It fails constantly, because desktop design puts price beside the image and mobile stacks it below a gallery that eats the first screen.
Shipping cost appears before checkout. The single most reliable cart killer. Cart abandonment sits between 70% and 74% across meta-analyses and unexpected extra cost is the most-cited reason. A shopper who commits mentally at $40 and meets $52 at checkout doesn't feel like they got shipping. They feel misled.
The product page answers the actual objection. Every product has one question standing between interest and purchase. Will it fit. Is it real leather. How long does it last. Will it work with the one I already own. If the page doesn't answer it, the shopper leaves to find out and mostly doesn't come back.
Images show scale and use. A product on white is a catalog. A product on a person, or next to something whose size everyone knows, is information.
The primary action is obvious on a phone, one-handed. Thumb reach, not just visibility.
Returns policy is findable in one tap. For anything with fit or feel, this is a purchase blocker, not a legal page.
The ones that are mostly cargo cult
Repeated because they're repeatable, not because they were measured.
"Above the fold" as a universal law. People scroll. They've scrolled since 2005. What matters is whether the first screen earns the second, not whether everything is crammed into it.
Reducing clicks for its own sake. Three clear steps beat one overloaded page. The goal is certainty, not brevity.
Removing navigation at checkout. Sometimes right. It also traps people who wanted to check one thing, and they leave instead of leaving the funnel briefly.
Chasing a specific page-speed score. Speed matters and score-chasing doesn't. Shopify retired its own speed score for roughly this reason.
Trust badges everywhere. A row of badges nobody recognizes is decoration. Real reviews and a clear returns policy do the work badges pretend to.
Personalization before you have traffic. Splitting 4,000 monthly sessions into six segments gives you six samples too small to learn from.
Why the lists don't work
Because "best practice" is a claim about stores in general, and you don't run a store in general.
A rule that lifts conversion on a $30 impulse product can flatten a $400 considered purchase. Long copy is bloat on one and the whole job on the other. Guest checkout is obvious for a one-time buyer and wrong for a store built on reorders.
The list can't know which you are. So it hedges, and hedged advice produces hedged changes.
The fix is a pass bar. Not "make the price prominent" but "the price is visible on a 375-pixel viewport without scrolling." The first is an opinion you can argue with. The second is a check that passes or fails, and two people looking at the same page get the same answer.
That's how our audit is built: 500 checks across the store, mobile and desktop, every page, each with a bar. We wrote up the hand-run version as a 30-check CRO audit if you want to do it yourself on a Saturday.
How to tell which applies to you
Rank by how much of your revenue passes through the surface.
Everyone lands somewhere, so the landing page and the first screen touch all of it. Most people reach a product page. Fewer reach the cart, and fewer still reach checkout. A 10% improvement at the top of that stack is worth more than a 10% improvement at the bottom, even though checkout feels more urgent.
Then split by device. Mobile session conversion runs around 1.2% against 1.9% on desktop, and most traffic is mobile, so most audits should be mobile audits. Most aren't, because they get run on the monitor that happens to be there.
Then test the thing you changed. Not the whole redesign. One change, one verdict, against revenue rather than conversion rate, because conversion rate can rise while revenue falls.
That last part is what we built Qosmic to do. The audit finds it, we build the variant, and we adjudicate it against real revenue, so the best practice either earned money on your store or it didn't. Plenty of teams run the same loop with a developer and a testing tool, and that works fine. It's the same loop either way. The question is whether it happens every week or whenever someone remembers.
The short version
- Six things reliably matter: visible price on mobile, honest shipping cost, the objection answered, images with scale, a thumb-reachable action, and a findable returns policy.
- Several famous rules are repetition rather than evidence.
- Best practice is a claim about the average store. Convert it into a pass bar before you act on it.
- Audit mobile first. That's where your traffic and your worst conversion rate both live.
- Judge changes on revenue. Conversion rate alone will mislead you.
