When I was 10 years old I used to go door to door with my lawn mower asking to cut grass. I used to make $50 or $60 a week charging $10 a yard in the Summertime. Quite a bit of coin for a 10 year old in the 70's.
When I got into tree work I started out with some tree gypsies who would door knock. Not that there weren't excellent climbers to learn from, on the contrary, there were a couple of excellent climbers and salesmen I learned from. I worked with a guy my first three years that went from solicitor to big time with 2 full page yellowpage ads. I literally watched and helped him grow into something to really be proud of. Probably the best experience I could have ever received. I learned all aspects of the business from this guy, climbing, sales, efficient ground work, how to survive.
When I started out on my own I made his plan my own. I would door knock and solicit. Back in GA we had many dead pines. I would cruise neighborhoods and knock on doors with dead trees in the yard, introduce myself and tell them my company name, explain that I was working in the neighborhood and was giving really good prices while in the neighborhood and ask them if they would like me to quote them a price. Most were nice but you will get a few doors slammed in your face. Goes with the territory when your a salesman. Any good salesman can't be afraid to get a door slammed in their face or be rejected. You have to be thick skinned and not take it personal. I consider door knocking a form of guerrilla marketing. Guerrilla marketing is used by the best salesmen in the country no matter the profession. Hell my folks sell real estate and put out neighborhood news letters and go door to door delivering the news letter (flier) with info in it like what's been sold in their neighbor hood and how much. They offer free market analysis to people and let them know what their houses are worth and develope a lot of leads in doing so. You could print up brochures with proper tree care facts and deliver them door to door as an entrance. A good salesman will beat the bushes when times are slow. I normally do mass mailings of fliers but will post them on doors and mailboxes sometimes. I usually don't go door knocking these days but will definitely speak to someone if they are outside in the yard. Just haven't been hungry enough to door knock lately. Don't be ashamed to knock on doors, salesmen of all varieties have been doing it for eons. A good salesman does whatever he has to (ethically) to make the sale.