I agree wholeheartedly. Be upfront and treat them, and their land, with respect. If you follow any Metal Detector's Code of Conduct, you've already talked to them (prior to the hunt) to obtain permission. That is the best time to negotiate any division of finds. In my 38 years of detecting, I could count the number of times I've been turned down (to hunt), on one hand. And of the hundreds and thousands of places I've detected, the number of people who actually wanted a share of the booty could also be counted on one hand. I always ask if they are aware of any personal items (or family items) that are suspected to have been lost in their yard. I let them know I will pay special attention to those type of targets and will be happy to return them. Just because they are lost doesn't mean they were discarded.
We all need to be aware of, and interested in, what all this hobby has to offer. Not just interested in the number of finds we might make. This hobby provides an excellent platform to learn more about local histories and the people we call our neighbors. Just like Smith1 said, share (with them) any history you have about their property. You might put them more at ease by sharing some of the trials and tribulations you've encountered in past hunts. And whether or not they are interested in what you have to say, above all else, be respectful. Afterall, it is their property. JMHO HH Randy