I had a friend who used to install peep holes on doors. He would go door to door and try to sell his peep hole installation service.

Usually, he would get 2-3% of the houses he knocked on to buy his services. He would install the peep holes in 15 minutes and be off.

He later managed to get this 2-3% to 20%. What he did was revisited the houses that had refused his offer during the first time - and told them: so and so of your neighbour installed it. Would you want to install it too?

He later on bumped that 20% to an insane 90%! How? Got endorsement letters from the local fire houses. And from the homeowner's association.

The strategy teachers may call this the Bowling Pin strategy. He simply called it "saturating an area." And getting approvals from the influentials.