How your website is designed affects your customer experience on your website. A good design will help usher customers through your site. It is important to keep in mind some key points in designing your website. I'll sum it up by keeping the focus on the products. Everything should point people to look at the product (or service) that you offer. That is the reason that people are there. Things that can distract a user are overly bright, distracting, or muddy colors. Using a picture as a background can also be distracting.
Take time to look at options for how to receive payment. See what your site builder offers as well as third parties such as Paypal. These can help to broaden your reach, but I would also be careful to not use too many. It can be better to start with one and add additional ones as needed or requested by customers.
All in all, building a site will take trial, error, and research. But thankfully you can make changes as needed.