A few more things came to mind...
Tom_in_CA said:
have some stuff to show that you found nearby (a vacant lot or whatever). That usually helps break-the-ice, and lead in as an introtroductory reason for asking if you can "check their yard" ........ as you "suspect more such fumble-fingers losses would be in their yard as well"...
Also helps to not have to "knock" to begin with (we all know what we say/do with door-to-door salesmen, eh?). Better to catch them when they're out in their yard (sitting on the porch, doing yard work, or whatever), and strike up conversation. Be sure to have your detector in-hand, to lend to the visual "what are you talking about?" aspect. To have to go back to your truck to get it, is an immediate "no".
Tom, I hate to disagree with you. You make some excellent posts about the intricacies of the permission issue... But I will respectfully disagree with you here.
It is a Rare person alive today who doesn't know what a metal detector is. I've knocked on thousands of doors, and I cannot think of an exception to that rule.
Don't worry--if they don't understand, they will ask you! But you don't have to ask them if they understand what your hobby is (it may make them feel insecure, which will NOT help your odds of getting a "yes").
Another point I must disagree with you on Tom, is that I believe one should leave their gear in the car. I even go so far as to walk up without my hands in my pockets, because I do Not want someone thinking I have a firearm in my hand. (If you live in Texas, make Double Certain that no one will think otherwise!)
I personally do not like the "check their yard" phrase. The owner may say "What's wrong with my yard?" or "What are you checking for?"
I prefer to ask if they would allow me to use my metal detector in their yard for a few hours. It is a phrase that almost everyone will immediately understand, and its clarity is it's strength. Be direct and clear in everything concerning permission--both Verbally and Physically. (One example on the physical side is to be sure to look the owner in the eyes when you speak to them.)
A few finer points: Use of the word "Allow" I have found to be Very important. It gives them the power of decision-making, and it shows them that you realize that they are in charge. This puts them more at ease with you, and it puts you in a position of humility.
I Always err on the side of humility. I don't try to buddy up with them. (If you do that, they will catch on mighty quick that you're buttering them up, and you will be more likely to get a "no.")
What you want to project is a sense of Calm Politeness.
Like what you have to ask them is the Smallest of requests--one that they'd be silly to cause a fuss about.
And keep in mind that in order for them to be at ease with you, you have to be at ease yourself when you approach that door.
I ALWAYS put a time constraint on the hunt. I want to make sure they understand that I won't be camping out there all day. I want them to know that I will not hold them up or interfere with their daily lives.
Now I might bend that a bit, but the way I see it, it's a matter of being true to my word and upholding my end of the bargain. Besides, you CANNOT build a rapport and sense of trust and respect with the land owner from just one hunt. It is a few repeated visits, spaced out over the coming weeks or months where you win acceptance. This is also the stage where you will be able to glean sites from them, their relatives, neighbors, or friends. If you ask them questions about the history of the area, local stories, tracking down owners of other sites, etc--make SURE you write it down. Don't put yourself in the position of having to ask the same questions twice! And don't expect to remember it all. You won't! Maybe after talking to the first dozen property owners--but Not after you have met thousands of people.
ALWAYS talk to the owner each time you hunt, before you start, unless they tell you otherwise. And ALWAYS let them know when you're leaving. Always! It lets them know that they have their privacy once again, and it is just plain old fashioned respect. It gives you another chance to thank them for the Privilege of metal detecting.
If you get a "No," don't let it ruin your day. Don't think mean thoughts about the owner, or hold a grudge in your mind. Move past that "No" quickly and get yourself in the right frame of mind to knock on the next door. Remember, it's their Right to say yes or no. You have No right to detect anywhere except on your property. We owe it all to the property owners.
Humility. Respect. Courtesy.
These three will take you far.
Regards,
Buckleboy