I have sandy soil also. Great for drainage, but a nightmare to keep watered in the heat of summer! My husband order a truck load of clay...BIG mistake. I can't get it incorporated, so it sits on top and makes a slippery, sloppy mess when wet. Your best bet is to keep incorporating organic matter, like compost, mulch, cover crops in the off season, etc. Where are you in Texas? I am just north of Bryan-College Station. I grow the heck out of tomatoes, potatoes, onions, and cucumbers. I can't seem to get the hang of green beans or green peppers (but I grew awesome jalapenos with very little effort last year.) I planted carrots, but got only a couple of little ones, so it wasn't worth the effort. I tried watermelons one year, but they took up too much space.
My best advice, other than have fun with it, is to jot down notes every few days. It doesn't have to be any fancy, just make notes about the weather, what dates you planted, names of varieties, how things are growing, what worked or didn't. You might think you will remember next year, but I promise, you won't! When you are standing in the garden center looking at all those tempting plants and seeds, it help to have notes to remember which tomato tasted great, grew well, etc. You might also check with your local co-op or extension service to see if they do soil testing. No need to spend money adding amendments that your soil already contains, or you might need to tweak a little here or there to get the best produce. Read, surf the net, and network. Gardening people LOVE to talk gardening!!!