1. Know what you're looking for.
Do you need something more formal for big-shot meetings and baller dinners or something more chill that says "I look fly but I don't work too hard"? The two areas that generally define how dressy a suit is are the lapels and the pockets. Thinner lapels (roughly 2 1/4 to 2 3/4 inches at the widest point) are more elegant, while thicker lapels (3 to 3 1/2) are more executive.
As for pockets, flapped or jetted (tuxedo-style) pockets are the standard, while patch (rounded) pockets give your look a bit more a laid-back vibe. Peaked lapels (the pointed joints) are a bit more rakish, while notched lapels are more classic.
Napoli Grey Faux Uni, $469, available at SuitSupply.