Just make sure your site looks super-professional. Make sure you also fill out any forms you may need for tax purposes. And do not underestimate how difficult it is to get over 5, users. Take your time to come up with a catchy, meaningful, and easy-to-remember name that would give people an idea of what your website is specializing at.
To be a member of the ABIA you need to adhere to a strict code of practice, which you can then show to any prospective clients before entering into an arrangement.