Giving it a little consideration though, if the OP were to put up a website that could RAPIDLY convince me...
One of the hardest things is selling an "intangible" service. A website will go some of the way but, as I'm in a similar business now as the OP, I am building up testimonials and references.
A word of warning in the form of an anecdote. This is the sort of "positive" referral you don't want:
There's a lady in Brighton who offers to run social media campaigns and someone in my network hired the lady for about 3 months. He said to me a while ago how great it was, she was posting on Twitter and Facebook for him every day, she built up the number of "Likes" and "Followers" his social media accounts had.
I said to him, "That's great if it's what you hired her for". He paused and then replied "Well, actually I had hoped having her run the campaign would bring more business in". I asked "How much have you had?". "None" he replied. "But she was very approachable."
Yes, she probably was very approachable, but she also charges several hundred a month and for what...? He had hired her nearly nine months before for three months, and since then had not seen any increase in business thanks to the campaigns she had run for him.
My advice is get yourself out there and known. I'm am (slowly) building up clients, and do have (three) testimonials on my site, but I am also going and doing presentations and building up my reputation as an "expert" in this field by writing articles, etc. You need to be able to show that your advice works for your own business. You need to get clients from your own social media expertise. If you can't do this, then people are going to wonder how good your service is.
When I was doing the previous service, at least 80% of my clients came from networking, both face-to-face and online. Our second highest-value client came through Twitter (and we had several others). I got clients through Linkedin as well and of course I'm always harping on about how great UKBF was for new clients.
As it happens, tomorrow I have a meeting with a local business owner who wants to increase his customer numbers. Rather than having me teaching him how to promote himself through social media (he doesn't have time), as I always frequent his business he wants ME to run the social media campaign for him. Therefore, my "expertise" (ahem!

) will be tested.