THe USDA puts out an ag book every year or so. Back in the 70's or 80's they put out a great book called "Living on a Few Acres". A lot of good information, it gets into the advantages and disadvantages.
The key to self sustainable living is to start now doing what you can and increase your sustainability while you learn more and get better skills.
In my mind the first step is not buying a lot of prepared food. Learn to eat about 80% of your calories on basic commodity foodstuffs. Example, instead of buying chicken cut up for you, you can buy it at 1/2 or 1/3 the price as a whole hen. Cut it up yourself. Boil and mash your own potatoes. Make your own pot of beans. Try gardening and if you are able learn to make meat with fishing, small game hunting, and then hunting large game.