We are a cleaning business. So we already go to people's homes. We decided to leave door hangers only in the homes within the same block as the home we already go to, we did away with covering an entire neighborhood, its time consuming and we rarely get inquiries from that. Our door hanger now says:
"We cleaned your neighbor's home today__(date)__, if you sign up by __(date)__ we will give you a credit of __(%0ff)__. We will be happy to do this because our transportation costs will be cut by __(%)__."
Along with our door hanger we also put in a coupon to Bar Keepers Friend (which they supply). It is a MIRACLE cleaner, and shows the customer we only use the best when it comes to cleaning agents! And because bar keepers friend knows how awesome this marketing technique is they also send us samples of their cleaning agent so we can include with our door hanger.
So it goes from your average "throw away" hanger to a "hmm... what is this goodie I see" hanger.
This is more of an idea to get your creativity going, feel free to replicate or add your own spin. I hope you find this useful and can figure out how this technique could work with your own offline marketing!