What are the rules when asking to take a photograph on someone's private property?

I am starting a bath and body company and until I make the big bucks, my daughter is my only model. We have been driving the countryside looking for great places to take photos. We found 2 perfect places that happened to be private property. I plan to just go to the door and ask for permission. But should I take something for them to sign, offer money? If so how much?