Dave H. has an excellent point. You may not know the landowners perception of hunters and unfortunately there are a lot of people out there that don't have a very good one. Show up clean cut and prepared. Offer him venison. Food is always a good tool. Do what ever you can to let him know you are responsible and respectful of others. It's his/her backyard you have to make them comfortable that you won't abuse it.
Once you do get on a piece of land you have to of course follow through with your promises. Go out of your way to help the landowner out. Clean some branches after a storm or spring cleanup. Fix a fence or a porch. Take a trashbag and clean the roadside of his property of debris. They may welcome the extra help with open arms and you could stumble on a prime piece to hunt on for years to come if done right.
One other thing you should consider, make certain you know if anyone else is hunting the land. If so you need to talk with them or find out what the deal is. good luck