Show, not tell
I have a special skill sets that could be very valuable to your business. I think we could work together. Though we have never worked together before, I am confident that we would be a good match and my service will bring value to your business…
One of the flaws of human (ir)rationality is our tendency to judge others by their actions and ourselves by our intentions.
If you want to prove your worth, take small, iterative steps. However, also remember that to grow, you need to be on the edge.
First, show it to yourself.