I cannot stress how important building your organic garden with raised beds can be.
The perfect bed should be 4 feet wide so you can weed and tend to your plants without disturbing your soil. Your length can run as long as you want. As far as your height I reccomend at least 8 inches.
By eliminating pathways in between your plants you have more room to fit more plants.
Raised beds also give you a deeper root zone so your plants grow healthier and more productive. You can also plant closer together because your roots will grow downward and not all over the place.