A small raised bed--we used a 4- x 4-foot kit--offers a plentiful yield without an overwhelming amount of effort. Put together your own planting box, or purchase a kit such as this one from Gardener's Supply Company (www.gardeners.com, #36-487, $189). The assembly gives you a good workout and has you ready to grow in about an hour.
Location is key. Vegetables require at least four hours of direct sunlight, with summer veggies benefiting from more. For easy watering access, place your bed where a hose can easily reach it; better still, buy a rain barrel and use collected water. Remember, a garden close to the house gets tended more readily than one behind the garage.