Basics for Men

Buy quality and take good care of your clothes.
Be trendy, but not a trend-worshiper.
Find out what’s in style so you’re not wearing a fad that’s over (like cargo pants, which are so out).
Buy the classics: jJeans, khaki pants, Tshirts, sweatshirts, sweaters.
Update your wardrobe with accessories

Also it's not easy for a teen male/guy to know what’s in or out. So i suggest that you watch how other guys put things together.
Research magazines, TV, movies, rock groups, walk through department stores these are good sources BUT remember just because a new fashion trend is in a store or on a boy band doesn’t make it right.

A few years ago i came across this simple guide (below) to help which choosing clothes and looking good, hope it helps

"Colors
You can compliment or contrast. Here’s the lowdown:
Complimentary colors are closer together in shades. Produces a more subtle look: Blue and green, khaki and gray, orange and red.
Contrasting colors play off of each other. A bolder look: Black and white, navy and khaki, denim and red.

Layer
Choose either complimentary or contrasting colors (to avoid a just-rolled-outta-bed-and-threw-something-on look). Try these:
Tee + polo
Tee + oxford
Tee + sweater
Tee + polo + sweater
Tee + polo + oxford
Tee + tee.

Accessorize
Your shoes and belt should be the same color. Black with black, brown with brown.
A rugged necklace made of leather, shells, or big beads can really pull an outfit together.
Use hats in small doses. Baseball caps can be totally out of place worn with jeans and a nice top. A newsboy cap can be pulled off by only the trendiest guys. If you insist on sporting a topper, try a stretchy knit cap (best for fall/winter) or a sporty visor (best for outdoors).
Buy cool shades.

Do’s
Experiment with styles. Urban; Prep; Sophisticated; Artsy; Retro; Mod; Punk; Surfer. Try to mix different looks.


Don’ts
Avoid the head-to-toe baggy look -- it’s just not flattering. T-shirts that reach to your knees will make your legs look two inches long (plus those extremely wide-leg jeans won’t help!).
Skip the athletic socks with non-athletic shoes. Doesn’t work with loafers, oxfords, leather boots, and most importantly, Doc Marten-style leather sandals. Ever.
Pass on head-to-toe logos. Mixing labels = good. Mixing over-the-top logos = tacky. When it comes to designer sigs, less is always more. "