I try to find the owners outside so I can strike up a conversation, just some small talk, and if I see they are senior citizens and it appears that they have some yard work to be done, I offer to help. Afterwards is when I ask for permission. I have helped an older gentleman out who has a bad back, I helped clean out an apartment for him. His yard gave up the most IHP's I ever pulled at one site. For 3 hours of labor I was allowed to hunt his yard for a 3 month period. Most don't want to keep anything and like TerryC stated never offer 50/50 split or else the owner will be hovering over you. If they seem interested in the history of the area I usually offer up a relic or 2. I had one owner give me permission with one stipulation and that was if I found 2 old coins of the same type, that he'd want the less valuable one. Needless to say that is the yard I dug the 1877 IHP. He got a thank you card with an IHP inside. There was another yard where I dug about 4 bucket listers. I also dug enough clad to cover a 6 pack of the owners beer of choice, just as a thank you. He didn't ask me for anything, but I was so elated at the amount of quality finds from his property that I just had to offer up the 6 pack.