The only things I usually grow are radishes, mustard greens, onions, beans, peas, tomatoes and peppers. The radishes did great in the container and provided ground cover for the container. The onions did not take well to it. The mustard did well until the heat killed it. I had already been told that beans and peas don't do well in containers (or, rather, don't do well in potting soil ... they apparently like sandy loam for their roots), so I didn't try them.
The tomato and pepper plants I bought at the gardening shop for about $1.50 each. Since I only grow four to six of each, the extra expense for buying plants vs buying seeds and starting my own is not much.
As for the containers themselves, I bought some plastic tubs at the hardware store that were each about 30" long, 20" wide, and 18" deep. I think. I made sure they were water tight up to at least 4" from the bottom, then drilled 1/4 " holes at 4" from the bottom around the perimeter. In retrospect, I wish that I had drilled these holes only on the side facing the edge of the porch so I could overhang the edge just a bit and not have overflow pouring out on my porch.
I used some 4" drainage pipe I had sitting around ... one length as long as I could fit into the bottom of the tub (catercorner) connected to an L then connected to a piece that was up the side up to ground level. Any size will do, you just need a way to gauge whether the gravel layer is wet and have a way to get water down there ... you want the plants to access the water to coming up from the bottom, not down from the top.
I filled the bottom 3" or so with a bag of gravel ... the cheapest bag I could find at the hardware store. Any gravel will do. I covered this with landscape fabric to make a bit of a demarcation between the soil and gravel layers. I filled the rest of the tub up with potting soil. I soaked the soil with water and gave it a day to drain down, then planted my seeds and little seedlings. Water every second or third day until water starts pouring out the drain holes.
Watch your plants and if they are wilting, they need water. If the leaves start turning different colors, they need nutrients. I can't tell you what color means what, but the info is out there. Check the web or call your extension office. They should know. After about July or so, I started pouring one gallon of water soluble fertilizer (like "Miracle Grow") onto the plants in each container once every week or two.
I put out this year's tomatoes sometime in mid-april, and I have three very, very green ones on the vine right now and a whole boatload of blooms.