Two things that can improve even the most questionable articles of clothing:
1) Being ridiculously good looking.
2) And the one with a little more flexibility: the fit.
Hands down poor fit is the problem most guys have with their wardrobe (probably for women as well). Fit can be tricky, but it can work wonders: accentuating or faking the perfect shape.
Chances are your jeans are too big and too loose. Now, I’m not saying you should run out and buy women’s jeans (you aren’t in junior high), but you should not be able to fit both of your legs into one pant leg. A properly fitted jean should make it obvious that you do, in fact, have legs, even if you can’t see every inch of them. Everyone has their preferences when it comes to pants—personally I am a solid supporter of skinnies on those who can pull them off (let’s not go there if you can’t, we’ll find a jean for you some other time)—but regardless of style, if they fit they will look more polished and fashionable.
Suits are another tricky area. They should be a higher quality (and probably more expensive) part of your wardrobe, for which you should be fitted. In nicer shops and even most department stores there is someone to help you find the right size. Note, however, that these are generally older men that aren’t as trendy as we are, so don’t be afraid to try a smaller size on than they recommend. Most men buy clothing too big. If a man’s clothing is too small, it probably means he has…expanded.
Also, anything nice like a suit or a really good jacket can be tailored. It is a good option and honestly we should probably all be tailoring all of our clothes, but it’s expensive so stick to the important pieces.
As I said, most men tend to buy clothing too big. This is probably because they don’t understand how proper fit works (or looks) with the body. I understand the urge to cover problem areas with extra fabric, but all that loose and flowy stuff just makes you look bigger. However the crime of oversized clothing is far more tragic on the skinny man. As is the case with many I know, skinny men tend to be afraid that smaller clothes will make them look even skinnier. False. Drowning in your clothes makes you look puny. You slender types are the ones that can pull off the trends, and if that’s not enough of a reason to change your ill-fitted ways, trust me on this: everyone looks better in properly fitting clothes. Everyone.
See this handy GQ slideshow for a little more advice.