A good user interface means more conversions and more sales, visitors, money.
If you want to learn how to build one, GoodUI is a good place to start.
GoodUI lists user interface tips that can help boosting your conversions. You can subscribe to receive updates twice a month, not too painstaking for a professional designer.
P.S. ‘Never take advice from someone who needs it’, says the proverb. The UI of the website is fabulous, so you needn’t afraid of bad advice here!