Depends on what kind of look you want.
Since I'm from Texas and also in a fraternity, I feel that I have a bit of a different style than a lot of other members on this board.
What I usually wear to go out is a nice button-down shirt (also called a sports shirt) with either 6"-8" inseam chino shorts and boat shoes, whitewashed wranglers and cowboy boots, or slacks and loafers or boat shoes.
On a regular, laid-back day I just wear a t-shirt/short sleeve polo shirt, chino shorts, and either boat shoes, running shoes, or flip flops.
A classic look that everyone will look good in is the: navy blue blazer, light-colored button-down shirt, and slacks preferably light colored.
If you want to go for semi-preppyish/boating/golfer/old south confident look, get these into your wardrobe:
Sunglasses: Ray-bans
Top: 4-6 sports shirts of different colors, 3-5 dress shirts, a variety of polos, and several t-shirts.
Bottom: 2-3 slacks, 2-4 chino shorts (I like a smaller inseam), a couple athletic shorts, and a few pair of nice fitted jeans.
Shoes: Boatshoes, loafers, running shoes, flip flops.
As for brands, I'm not too familiar with the more formal businessy brands, but you might want to take a look at brands like: Vineyard vines, Southern Tide, Southern Marsh, Coast Apparel. Check out their websites.
Here's an example of that kind of look:
http://s3.amazonaws.com/wegoall/bscsigmachi.com/galleries/808/1297108830929.jpg