The first, most basic, and most overlooked idea behind a successful vegetable garden is this: plant what you love to eat, as much as you can eat, and you'll love harvesting and eating it. Beyond that, you can venture out into interesting vegetable territory with some less traditional gardens.
Succession planting, according to Jeff Bredenberg's "How to Cheat at Gardening and Yard Work," means that "instead of having your garden's production stagger to a halt, you will be extending the harvest season." Here's how it works: when your patch of lettuce has been harvested, pull up the dying plants and pop some radish seeds or seedlings in their place. When your corn has been harvested in late summer, pull out the stalks and put in a patch of spinach. You'll be pulling in produce well into fall.
Gardeners tend to think in terms of the linear: how many plants per row or how many square feet per raised bed. Limiting yourself to the horizontal means you miss out on the plants you think might not fit. Grow your vining plants up instead of out--think trellis, poles, arbors. Add fruit trees in the corners of your garden or along the north side as a permanent (vertical) addition. Put in a high fence to keep out deer and other animals, and plant blackberries along the length of it.
Heirloom vegetable varieties are distinctive varieties, producing a quality of fruit above and beyond what you'll find in any grocery store--purple tomatoes, white eggplants and striped peppers. Convert your plain-Jane vegetable patch into a showcase for carefully preserved heirlooms by replacing your regular plants with a selection of heirloom varieties. You'll be preserving a genetic legacy as well as producing a tasty crop.
A vegetable patch isn't all about function; it can be pretty, too, even after the squash blossoms are gone. Plant flowers in your vegetable garden--add them as borders, ring them around raised beds, intersperse them among your okra, put them in between your peppers, and fill up that one empty row instead of fighting weeds all summer. Annuals of any kind will do--zinnias, marigolds, poppies, cosmos, salvia and nasturtiums.