Air conditioning and heat are musts, and I would suggest going overkill rather than under. People think of the cold up here in Minnesota, but I get just as much enjoyment out of that big 22,000 btu airconditioning unit in the wall of our garage.

I like pegboard on the walls, but I noticed the standard brown chip color just seems to absorb shop light. If you put some up, paint it white first, really helps reflect light and just seems brighter. Also, don't run the peg board all the way up to the ceiling, especially if you have to lean over a bench to get to the peg. You can find out that the top half of your peg board is unreachable without a step stool.

when setting up my garage workspace (nearly 800 square foot 3 car garage), we added a seperate sub-panel for the electric with a 50 amp breaker on the main panel. This made it easy for the Heat breaker, Air conditioner (220volt) breaker, additional lighting, and running extra outlets through conduit and exposed boxes. For a workshop, I like the conduit, as its easy to modify later without ripping out walls and cheap and easy to install. I ran two sets of wires with breakers for all of my electrical, so that the left side of each 4 outlet box was on one breaker and the right side of each box was on a seperate breaker to help break up the load.

the biggest suggestion I can give, is to keep the stuff you actuallyl use frequently in places that are convenient, and the stuff you break out once or twice a year up high, or tucked under in a cabinet somewhere. Good labeling of bins and cabinets is also very helpful, and if you can keep common items in the same area. I have one pretty good sized cabinet where I keep all of my paint, chemicals, airbrush, masking tape, primer, sandpaper, etc.. in. I know if it has to do with paint, prep, or chemical, its in that cabinet. Once you get use to your setup, its much more efficient.

With lighting, you may want to look at both flourescent and possibly track lighting. I have some track lighting that aims light directly on certain areas (band saw, main work table, vice, etc..) I like the track light, but the bulbs seem to give off a bit more heat than the flourescents. This is nice in Minnesota, but may not be advantageous in Texas.

Good luck, can't wait to get a new work shop going. Mine is sitting vacant, waiting for a RC modeler to look at my house...