The most dramatic improvement you can make in your style is to make sure everything fits impeccably. Most guys wear clothes that are too large. Make sure everything you wear is almost hugging the shape of your body – without being tight. Bad fit is an epidemic.
You want a wardrobe that looks great on you, but don’t overdo it. Don’t wear more than three pieces of jewelry or more than three colors. Don’t dress like a rock star unless you’re in a band. If you want to be flashy, a simpler but stylish look would be sporting a black striped dress shirt with a white blazer, a dark pair of jeans, a dressy belt, and your sharpest dress shoes. You could also add a flashy watch or a simple accessory like an interesting necklace, but nothing more.