I would buy some books on Amazon. Some of my favorite sales books are by Jeffrey Gitomer. Quick reads and very practical advice and approaches.
Not sure if you have a specific niche or market or if you are canvasing an entire area of local businesses.
In general it helps to have a "warm" call or introduction versus a "cold" one. For example, calling someone out of the blue and pitching them something is much harder than if you send a few engaging mailers first and in those mailers you let them know that you will be calling to discuss.
Then when you call them up you can reference those and that you are following up, and hopefully they will recall it.
Typically they say it takes 7 touches before you make the sale. But if you are giving your service away I imagine it will be a little different.
The best sales advice I can think of is that people don't give a crap about you or your product - they care about themselves and their businesses. So always remember they will be thinking "What's in it for me" ... don't break into all the features right away. Talk to them about what pains they might be having now, how your service could benefit them and make their life better and it's completely risk free to try (since it's free).