While the above dressing style tips may help you - build a more selective, tasteful and reflective wardrobe, it can take some time or depend on the acquired taste.
Some sure-shot ways of nailing this could be by upgrading your basic styles to more classic silhouettes like T-shirts, semi-formals and some solid accessories with watches, belts and shoes. However, a 360-degree approach to looking classy is more effective when the personality matches the style. Some fine ways of appearing more sophisticated could come from caring about others, complimenting others around and remembering things that are important to other people.