I bought the book "Square Foot Gardening", which is wonderful and often available at places like Half Price Books. But, you can just got to squarefootgardening.com and get lots of information. I have used this method for the last few years and it works great for stuff like tomatoes, peppers, onions, squash, zuchinni, etc. You may get a little smaller yield per plant, but you will get a larger yield per square foot of your garden. And, it tells you how to garden nearly year round, how to plant in rotation, add compost each time you replant a square, etc. It's a great system.
Also, you don't have to plant food plants only in a separate garden plot - put some in your flower beds!