Get a one-page letter explaining who you are and what you do, attach a permission slip that the owners sign, and attach a google map screen shot so that they can map out land boundries. Then, start visiting locations that you want to hunt. I do Sat mornings. Everyone is home then.
Also, run a craigslistadd as a "free extermiantion service."
Moved 4 states in 10 years. This is how I line up my land.
And when you get permission, bring a $3.50 Walmart Dutch Apple Pie with you to give to the landowners. Old people are helpless when faced with the unyielding power of pie.
PM me and I will email you my rights-request package. You can modify it.