It really helps to know your ethnicity/skin tone and what kinda scenes you hang out in... ANY article of clothing -regardless of how expensive/ what brand/ how nice- is a big waste of $ and will make you look dumb if it doesn't fit your style and personality.
Just for example, I'm a pale white dude who plays lotsa sports (grad student now)...
I wore baggy skater clothes and logo tees early in high school, then prepped it up a bit later in HS and in undergrad (RL, A&F, etc). Around the start of grad school, I dabbled in the Eurotrash high end stuff like Armani button-down shirts, tighter jeans, etc a bit. That was a big mistake and a terrible waste of $... esp because that stuff is built for rail skinny guys and not guys who lift and are average to muscular. You might have to play around a bit, but try everything on and don't buy on impulse... that's how you learn I guess, but also how you waste tons of $.
Now, I've gone basically full circle back to the prep style I guess: polo shirts or button down dress-type shirts mostly with some tee shirts mixed in some days too. I keep the jeans or khakis relaxed though, because that's just what I find comfortable. Bold solid darker colors are best for my skin tone, and I stick 90% to black, white, blue, gray and maybe deep green.
I really love the button down dress shirts, both vertical striped and solid colors (and wrinkle-free is KEY). They go fine with jeans for going to school or casual... I wear em untucked and with the sleeves rolled up and it looks good. You can also wear em tucked, nicely pressed, buttoned up to near the top, and sleeve cuffs down with a pair of slacks and look slick at out at the clubs or combo em with a tie for business situations. It's a flexible style that fits for me, I guess.
I think my favorite brands right now are JCrew, RL Polo, Claiborne, Kenneth Cole, Lacoste, and Tommy Hil. I shop online, Younkers, JCPenny, TJMaxx, etc. Classic whiteboy rich look I guess, but it's classic for a reason... it doesn't go out of style and it looks good. I still mix in some Adidas or Nike stuff too so that my style stays athletic, because that's basically me.