Before you can choose the right keywords, you need to get inside your customers head. Remember… customers are not searching for YOUR site specifically. They are searching for valuable information to solve their problems.
Having a buyer persona is a crucial first step in figuring out what your ideal customers are most likely to type into Google.
There are lots of resources online to create Buyer Personas, but my recommendation is to build your own, similar to the one below, based on your knowledge of your ideal client.