I feel that it would be important to mention that nothing is free. That being said, you have to ask these prospective clients (for whom you've never worked), "what have you done for me lately?" Don't sell yourself short!
You can't start giving things away until you know what your costs and profits are. I offer existing clients a 3% discount if they are willing to pay for a season of maintenance ahead of time. I used to offer a 10% discount, but then I started wondering where my money was going or, more accurately, had gone.