dnb,
Let's pull back for a second.
You "are a virtual assistant company and there are a lot of them out there."
Then the first thing you need to figure out is how is your company different from all the others out there?
What is the advantage of going with you?
This needs to be a difference you can deliver on. Do an honest assessment of your strengths and weaknesses - highlight the strengths and downplay the weaknesses.
Next, as it has already been stated, you need to figure out who would be your ideal target for your services and expertise? Do you understand a certain industry better than others? Narrow your vision for a better hunt to find clients.
Once you have decided on a target, then you need to craft your message so that it speaks to, not at, the client base you are looking for.
Start thinking about how to reach them?
What is the best medium for that?
What type of budget you can afford?
What is the tone or voice that you want to use for your company?
I know this might sound like a lot of work but you will be surprised how quickly it moves along, and how easily things will start to fall into place. But before you can go out to get clients, you need to know who you are talking to, what you are going to say and what is it that they need to hear to get them to use your company.
I hope this helps. I tried to keep it short. There is more I could tell you, but this should get you started.