All of you people are giving him "East Coast Prep". That's all well and good, but he's in Lubbock, TEXAS.
As a native Texan, Baylor Grad, and preppy dresser since (we won't discuss timelines), there is a bit of a difference.
All the vehicles you mentioned are fine, but you can add "Tahoe" (never Escalade, and Suburban is what your Mom drives), or any large 4WD Jeep product to the list. All preferably new. Stock only (no rims, no stereo). Ford, Toyota = out.
You buy regular LEVIS 501's (no designer labels). You send them to the CLEANERS (try to get the same cleaners every time). You want the CREASES down the front and back (like dress pants) and you want the creases PERFECT (must be exact about this).
In addition to the footwear listed above, Tony Lama (high heel, western) boots, in plain dark brown (no dingo boots, no exotic skins, no other colors).
You buy long-sleeved Ralph Lauren Polo oxford cloth shirts (white, blue, pink only)---the Polo pony is preferred, no other visible logos, and for God's sake no pocket on the shirt Poindexter---which you take to the same cleaners and have "heavy starch". You want the shirt starched to the point of cardboard (it needs to stand on its own if you take it off the hanger and put it on the floor straight up and down). Cuffs must be flawless. Collar likewise.
You wear the boots, starched/creased jeans, and the long-sleeved Ralph Lauren button down (you have tons of blue and white and one pink one). (Do not even attempt to wear or own a Stetson unless you are actually a rancher).
(believe it or not, the above is what I wore to school for 4 years, me and all the other little conformists. I had a roommate who organized his shirts by color, blue/white; about 5 or 6 each, all identical Ralph Lauren, all spaced exactly 1.5 inches apart in his closet).
Whatever you do, if you ride horses, do NOT ride English-style in Lubbock. You will, in fact, be shot.
Your hair needs to be short. For a black guy, this means the "traditional" extremely short hair, same length all over. Period. No other hairstyles available. (White guys have more options---bowl cut or crew cut, in Lubbock they prefer the crew cut while in Central Texas or Dallas and Houston, the bowl cut would work).
If you don't know how to ride horses, insinuate that you do. You learned on your family's ranch "in South Texas", which is comfortably far enough from Lubbock that you can get away with it. Your father "does something with oil, and of course the cattle...." is good enough. You really don't know a lot about what "Daddy" does, he just makes lots of money. If your father is, say, a doctor, he still has a "place" in the country (if it's under 100 acres, it's a "farm", if it's over 100 acres, it's a "ranch"--and you can drop in stuff like, "Yeah, Daddy just added a new tank...", which is Texan for "pond" (there are no stock ponds here; they are stock TANKS even though they're made of dirt and filled with water).
For "casual" wear, the loafers without socks, topsiders without socks, madras shorts, collar turned up polo, rules you saw above are good. (You still send the "polo" shirts and madras shorts to the cleaners---all your clothes go to the cleaners, you don't wash anything but your sox and underwear).
Cargo shorts = no. Hiking boots, thick socks, and shorts = Colorado, not Texas.
IZOD = gay. Polo, Nautica could go either way.
Somebody mentioned "squash" above---in Texas, "squash" is a member of the gourd family, you eat it fried with onions. Nobody here (outside of SMU in Dallas) has heard of it. Same with "Crew". "Preppies" here play soccer (which has vague communist overtones).
This is Texas. If you're not knowledgeable about football, get that way in a hurry. However, your knowledge should not be that of an "athlete"; in other words, you shouldn't have an actual WORKING, TECHNICAL knowledge of the game, just that knowledge you gained from PeeWee, high school, and watching on the sidelines---or in Daddy's box at Texas Stadium. DO NOT refer to the players by their first names (as if you might know them); refer to them by their last name, prefaced by "ol'" (short for "old"), as in, "Ol' Romo made it all the way through the game Sunday without throwing an interception!" "Ol' Williams made a great catch, didn't he?" You don't actually KNOW these people, they play for your entertainment.
Remember, if you're from Dallas, you grew up in Highland Park/University Park/Preston Hollow ("Park Cities"); if Houston, River Oaks, Memorial, or West University Place ("West U"); San Antonio, Alamo Heights ("Heights"). You graduated from (Dallas) Episcopal or Jesuit (Houston) Kinkaid (pronounced "Kinkaaayd") or Strake Jesuit or (San Antonio) Texas Military Institute (TMI) or Alamo Heights High ("Heights"). Your Mom only works if she's like, a cancer-researching doctor or something. Otherwise, she stayed home, and bought ALL your clothes from the same place you still buy them: the Polo Shop at Neiman-Marcus, NorthPark (Dallas) or Post Oak (Houston). Even if you're from anywhere else in Texas.
Have fun!