Asking and getting permission is an art. I've sat on both sides as a seeker and seekee. The more you can alleviate the fear of the unknown (you), the better off you will be. You may want to try getting limited permission, e.g. bowhunting by yourself, during the week, and does only (if that makes sense) - don't just ask an open-ended question, "can I hunt your land?" You have just 30 seconds to convince the landowner that you are responsible and safe. I teach Hunter Safety, and I believe it has helped when I say "I not only hunt safely and ethically, I also teach it." Offering to do chores never hurts either.
-fsh