RE: what is the best way to gain access to private land?
In person is the best, but if you really want to guarantee a yes, bring along a kid. My experience is that farmers/landowners might refuse an adult, but they have a soft spot for kids, as we all do. Of course, that's assuming you have a kid to take along. If you don't, rent one.
If you get access, be sure to:
Say thank you.
Check to see if other hunters also have permission, and, if so, try to find out who they are, where and when they'll be hunting, etc.
Follow up before the actual season--let the landowner know when and where you plan to hunt.
Close all gates, park courteously/out of his way.
Follow up with a thank you, successful or not. I like to write a thank you as well as stop by the place and shake hands. If I had success, I like to send along a picture of me and the dead animal, so they can recognize me next year.
I also send a gift at Christmas, if I haven't shown appreciation at some other time--my wife and I bumped into and then bought supper for a landowner couple that let us hunt their land, and got some new friends in the process!!
Don't rule out inviting the landowner along. There's a long story that goes with this, but one time I invited the landowner along, he said he didn't hunt but his son did. We became friends and now I stay at their place when I go there to hunt!! (There's much more to this story--my son's friend even wound up getting married to the farmer's daughter!!)
Don't think that because you get a yes once you have lifetime permission. Always check. I get to hunt one piece of ground when the landowner's son-in-law doesn't get drawn, but don't when he does get drawn. (I have offered to guide the son-in-law, as he's never taken a turkey, yet, but that's not happened yet.)
Don't think that because you have a yes for turkeys that implies a yes for deer, or upland, or what-have-you. Most landowners DO have a sport or time of year or attitude about certain game that may mean a different response at different times. Some folks LOVE to hunt deer, but don't care about pheasant, for example. But then they often don't want you to "spook" their deer if the deer season is approaching. Others absolutely don't want you to kill Bambi, but don't mind if you whack a turkey. In areas out west, I've actually had ranchers tell me to "shoot all those %!@&@^($@) turkeys you want" because they are a problem. (I limit my harvest to the tags I have, anyway, but that is an interesting thought, to me. Spend a spring harvesting turkey after turkey.) Yet those same ranchers charge big bucks for deer and elk hunters!!