I did Square Foot Gardening with a 3 by 17 foot space in a public demonstration garden. It received the most compliments and questions out of the 2000 square foot garden area. The method is a simplified form of intensive gardening.
Do: get both versions of the Square Foot Gardening book by Mel Bartholemew and read them both. Then content is different enough and informative enough to justify it and you should be able to find the first one used for very little. They contain everything you need to know.
Do: Browse and participate in this Square Foot Gardening Forum
Photos of existing Square Foot Gardens:Examples Page 1Examples Page 2Examples Page 3Examples Page 4Examples Page 5
Do: Go UP
If nothing else, try a 4x4 foot square. You can grow an amazing amount of produce in this space.
Don't: Not try the method!