I agree that prepping the soil should start ASAP.
Dig up the planned bed now to kill weeds or remove sod. If you don't grow veggies this fall, sow some cover crop to enrich and loosen the soil and keep the weeds down. Mulch like hay or straw or leaves greatly reduces weeding and watering.
Collect leaves, coffee grounds, paper, grass clippings, yard waste and kitchen scraps for composting or directly burying. If you leave them in a pile over the winter, you'll have great compost by spring.
Cover crops and compost can eliminate the need for fertilizer.
Know what veggies you like and what your family will eat. It doesn't help if you grow things that are easy and productive in your climate, if your family doesn't like it.
If it's cheap in the supermarket, don't waste space and time growing it, unless you want better-tasting and more nutritious version.
THEN, figure out if the things you want will grow where you live. Unfortunately, "Zone 8" only says the coldest an average winter is likely to get. I'm also Zone 8, but the coastal Pacific NorthWet is very unlike any part of Texas!
What-grows-well, and when-to-sow-it, and whether it does better started indoors in trays or pots, is a very local question.
I think that, in most parts of Texas, cool-season crops can only be grown in the Fall. Even heat-loving crops may need to be sandwiched into spring & fall, because mid-summer burns almost everything to a crisp.
Dave has a Fall and a Spring planting calendar under "Webapps".
Enter a zipcode or city and state
http://garden.org/apps/calenda...
http://garden.org/apps/calenda...
For example, from Dave's Fall calendar fore Dallas:
"... beans, cowpeas, corn, squashes, pumpkins, cucumbers, watermelons, gourds and sunflowers, you should plant those seeds directly into the ground around August 12."
"Most tomatoes, peppers and eggplants, for example, require around 100 days to harvest, therefore you'd want to transplant those into the ground around August 17"
Can you
water a veggie bed? That plus some afternoon shade may let you grow more things during a heat wave.
Try to find out what your neighbors plant and when they plant them. If you plan to start seedlings indoors, trade seedlings for seeds. Once you know you can grow certain things, offer to trade some of that variety for whatever a neighbor has lots of. They may already know what they like enough to grow, but would still try out some new variety that you grew. Like tomatoes or unusual greens.
Your local Co-operative probably has lists of crops suitable to local climate, but that should probably be at the County level, not state-wide. I'm not sure which counties are in central Texas.
http://www.csrees.usda.gov/Ext...
http://counties.agrilife.org/
For swapping plants and local advcie, try Dave's "Member Map" to find ATP memebers who live right near you. Hover your mouse over the dfots and sometimes a member names will pop up.
http://garden.org/users/member...
Last, if you don't get many Texans responding in this forum, try a similar question in the Texas forum. Mention your county and a few specifics like whether you have beds already prepared, good or bad soil, novice or experienced gardener, whether you plan to plant whole fields of corn or just a few rows of beans.
http://garden.org/forums/view/...
