The best gardening advice for Houston is to use raised beds. Almost all vegetables like well drained soil. In Houston, at least in the gumbo areas in the city proper raised beds are a necessity. In a separate post I described how I designed and built the beds. I had a semi raised bed garden previously so I did not need to haul in a tremendous amount of new soil. To fill in where I needed more, I got composted native mulch from Action Soils located on the 288 west service road just before Beltway 8.
I try to preserve the natural layers in the soil. Soil biology is a complex and synergistic relationship among the plant and the various organism in the soil. These organisms live in layers in the soil based on their position in the food chain. Disturbing the layers disturbs this relationship. Tilling the soil puts the organism that prefer to be deep on the surface and vice versa in addition to pulverizing all the worms. I try to keep the layers intact and just add mulch, the fuel for the system on the surface each year. I cut old plants off at the root line instead of pulling them up. For fertilizer I use Microlife and cottonseed meal for plants like corn that need a lot of nitrogen. One of the side benefits of this method is that weeds are much less of a problem. Tilling or spading triggers germination of the weed seeds. I have the beds in rows so that it is not necessary to stand on the planting area when planting, tending and harvesting. Walking on the beds compacts the soil.