Use a prototype to negotiate with the customer
This simply means that as all the artists, from a painter to a photographer, you should also need to have a portfolio containing your best works and as you work on the computer, you should also need a couple of templates you use as a base for your work.
Some of these should be done on a very high and professional level, so they serve as a prototype that you can show as a form of a reference to a client. This way, clients can see what you are capable to design and your methods in design too.
Also it is essential that you let the customer know that all of their wishes will be listened to and realized. Just like it happens with hairdressers, many clients would not dare to talk up and tell about their key requirements but would come back complaining after the job is done, that the website does not look like how they expected.
This is a major issue for web designers and that’s why you also need to learn about customer relations, so that the client would dare to open up and talk about his/her expectations.