I have a lot of years of successful door to door sales but honestly I keep it super simple. "Hi my name is James. On my days off I like to go out metal detecting looking for old coins like these here wheat pennies or the occasional silver dime.(At this point I hand them a couple of coins so they can't shut the door in my face
) That's actually the reason I'm on your porch right now. I see that you have an older home and I was wondering if I could do some detecting in your front yard.
Seriously that's it. If they give me any objections about digging holes and messing up the yard I just politely reassure them that they "won't even be able to tell I was here when I'm done".
Also, never ever ever bring your gear to the door with you. I keep everything in the car until permission is granted.
We went out hunting the last few days and heres how it worked out. The first day we went out we went to 3 houses that actually had people home. 2 said yes and 1 said no. Today we went to 3 houses. 2 said yes and 1 said no. All in all that's not too bad. I find for the most part yes is 50% of the time or more.
The next time we go out I will record a few of my door knocks and post them on my youtube channel:
https://www.youtube.com/channel/UCmyPi6fg1Kn3N5mB6rpJcgA
Get out there and get knocking, it will increase your silve finds tenfold. And remember, every door you don't knock on is a definite NO!