A/B testing is probably the best way to test the UX of your website. Any good design and development team knows the power of this kind of testing, and the surprising results it can sometimes reveal. But, to someone who is setting up their first website it can be daunting.
Whether you're a bootstrapping entrepreneur with no budget for a designer, or you're a UX designer trying to make the most of your first step up the ladder, it's important to know know some A/B testing best practices right off the bat.
Depending on what category your site fits into, you're going to want to test different things. For example, if you're a media site, you're going to want to test things like where your related content lives on the page (left side, right side, or bottom), or, the optimal number of site navigation choices. If you're a retail site, you want to drive traffic to popular products. That would mean testing for things like default sort options, or the size of ratings and reviews.
This infographic from the Optimizely 2016 Testing Toolkit gives a number of suggestions of things to test for different website types. There are tips for media sites, retail sites, travel sites and B2B sites. The toolkit contains much more than just this infographic. It contains a lot of resources that are new for 2016.