One of the easiest ways you can create customer confidence in you and your business is to post testimonials on your web site. Don’t even think of writing these yourself (I’m sure you wouldn’t) but ask your clients to write something that clearly states what you do for your client and how working with you has improved their business or life, etc.
If you are new to virtual assisting and don’t yet have clients you can ask for testimonials, prepare some case studies outlining a problem and how your service helped solve it. These case studies are also very powerful in convincing a potential client that you can do what you claim.
For more information about how to market your virtual assistant business, take a look at the VA Success Groups Marketing for Virtual Assistants Online Course