This answer will be relevant if you have run a website design business before and if you haven’t.

If you are solely wanting to focus on WordPress alone great it’s an amazing platform using by hundreds of thousands of people.

The first thing is to ensure that you can build what some clients will expect, check out some theme examples on google and WordPress itself if you can build that and better great.

You need to build yourself a portfolio of your proudest work, set up multiple instances of a WordPress website with each of your themes on (one per WordPress instance) and just add some dummy text (Lorum Ipsum). This will enable potential clients to view your work and get a feel for you.

The next most vital and can also be one of the hardest steps is getting your name out there among all of the other WordPress developers this can seem a really daunting task but with hard work and perseverance it will pay off.