What are the most common ecommerce design mistakes?

Hiding the delivery cost, requiring an account, and a home page slideshow nobody sees past the first slide. All three are decisions made for the business against the customer.

In more detail

The fourth is designing on a desktop for an audience that is on phones. Most stores in this region take three quarters of their traffic on mobile and are still built and reviewed on a large screen.

What to do about it

The photograph is usually the product page. Everything else is supporting it.

Most design decisions on a store are really navigation decisions, and navigation is what decides whether somebody finds the thing they came for.

A product page has one job. Everything on it that is not helping somebody decide is in the way.

The mobile app angle

The same screen designed several ways is the point: a catalogue of four hundred lines needs a different home screen from one of forty.