I've given a business card with my contact info to ranchers and have offered to help in any way I can. A thank you and an offer to help them for permission is the way to go IMO. After you get to know the rancher and come back to hunt the next year or even after your first hunt and while you are getting to know each other only then would I bring his fav drink of choice. For me it's been Crown and Coors Lite. But that's our boys here in Nv.
I don't Break the rules, I Modify them.
I have no western experience but I agree with the giving a business card with all info and showing genuine interest in the land and farm. I always ask if having any problems with trespassers and so forth and how I can help. I also send Christmas cards and homemade holiday cookies as a thanks. Never alcohol, people are funny about it.
I don't hunt private land much anymore, but my dad would always send a large box of See's candy with a personal note at the holidays. That way the wife and kids would enjoy it too.
One guy told me that a rancher he hunted with, liked to waterfowl hunt, so he gave him some premium shotgun shells. I always thought that was a clever idea.
Try to bring something from your local area that they don't see to much of out there. Being from Oregon smoked salmon wouldn't be a bad idea, Tillamook cheese too. Also something that wont spoil. A 1.75 of good whiskey probably wouldn't hurt.
Place I used to hunt I used to take him a 30 pack of his favorite beer whenever I stopped by there even if I wasnt hunting. Giving them something after you hunt is a nice way of saying thank you. I think genuinely respecting them and their land will get you farther then anything else will though.
Thanks for all of the ideas and advice.