Check their portfolio - a web developer's portfolio is the best way to get an idea of the type of work they do, and how well they do it.
Ask for references - if they have worked with clients before, it's a good idea to ask for references so you can hear firsthand how they did.
Consider their technical expertise - a great web developer should understand coding languages, such as HTML, CSS, and JavaScript.
Evaluate their communication - communication is key to any project, so make sure the web developer you choose is clear, responsive, and a good listener.
Take their turnaround time into consideration - you don't want to wait too long for your project to be completed, so make sure the web developer you choose can provide the timeline you need.
