So one of my personal pet peeves is when pollsters / solicitors / UPS men / etc come and knock on my door at night. I am a single woman who lives alone. I am NOT going to open the door for you when you are standing 2 inches from my front door at 9pm at night. Call me cautious, but that is how I am.
The reason I bring this up is that today, I had a perfect example of what TO do when knocking on a door. He knocked, then took a few steps back so he wasn't on the actual porch and didn't even approach the door after I opened it. He was doing local quotes for windows and bath tub liners and accepted my answers about just having them done and not needing a quote. No hostilities, no arguments.
Hurray for proper behavior!