Oil & gas investing. Help?

I have been entertaining the idea of investing in oil and gas for several years but have started to get more serious about it over the last few months. I have little to no idea how any of this works so please educate me. What is the difference between investing in oil and gas through a mutual fund and going to other states and asking landowners to lease to me? (Hopefully that's rhetorical correct verbiage?) I'm not looking for a get rich quick scheme because let's be realistic. However, the idea of some passive income even if it starts out as just a few hundred a month would be very beneficial. Not to mention the tax benefits. Would/could my financial advisor/stockbroker do this for me? I live in East TN so no oil fields around here. What's the difference in investing in oil and gas and "investing in an oil field" as I heard someone say awhile back? Sounds like investing in an oil field is much more expensive and to start with, I would start low and work my way up depending on profits obviously. Just looking to better plan for my future. Thanks for all the info in advance.