The same rules apply to the design of websites and e-commerce applications as to creating products in other areas, but there are some peculiarities. Here are some tips from https://fireart.studio/blog/e-commerce-application-design-tips-and-best-practices/ on how to make your e-commerce product more efficient.

Earn Trust
If the site or app looks unreliable, the buyer may find another place to buy.

To place the buyer in trust, confirm trustworthiness:

• provide general information, address and details, show people working in the company, leave links on social networks;
• post the rules of the store, which will indicate the terms of delivery and return, publish a privacy policy;
• publish reviews and reviews on products, this will help buyers find out more information about the product;
• be attentive to details: avoid typos, broken links, missing images. This can have a significant impact on the user experience.

Place your shopping cart correctly

Place the trash can icon in the usual place: in the upper right corner so that the user does not have to search for it. Show the number of items in the cart next to the icon, it is even better if the amount of purchases is indicated.

• Give the opportunity to save products for later by adding them to your "favorites".
• Cross-sell. Place on the cart page blocks with products that may be of interest, for example, "people are buying with this product."

• Offer to buy more. This can be done by adding a reminder that you need to purchase goods for a certain amount before free shipping. Or the same reminder with a gift or discount when buying a certain amount.

• Make sure that you can easily change the quantity of an item or remove it from the cart.
• Tell the buyer the final cost. If there is a promotional code, add the ability to enter it and find out the purchase amount, taking into account it. Include taxes and shipping.
• Make checkout and checkout comfortable
  Provide as many payment and delivery options as possible so that the buyer can choose the most convenient one;
• Eliminate optional fields for filling, value the client's time;
• Add the ability to purchase without registration;
• Leave the items from the basket in plain sight;
• Give an opportunity to leave a comment on the order;
• Add a gift wrapping option if it suits your merchandise.

Conclusions:

• To place the buyer in trust, confirm reliability: post company information, shipping and return policies, reviews and testimonials. Avoid typos and mistakes.
• Place the cart icon in the usual place, indicate the shipping cost and the total cost, allow you to change the contents of the cart, use cross-sell in the cart and offer to buy more.
• Make ordering and payment comfortable.