This. Perhaps i'm biased, since i'm supposed to graduate from philosophy department this year, but i do think that reading ancient philosophy (Plato & Aristotle are the most representative example of what was going on there) is the best way to think better -- and get in touch with origins of European culture.
My recommendations, apart from "Sophist" (which is a difficult, very technical dialogue regarding problems with platos theory of ideas) would be "Nicomachean Ethics" (Joe Sachs' translation), "Philebus", "Phaedrus", and of course "The Republic", Platos' magnum opus.
My recommendations, apart from "Sophist" (which is a difficult, very technical dialogue regarding problems with platos theory of ideas) would be "Nicomachean Ethics" (Joe Sachs' translation), "Philebus", "Phaedrus", and of course "The Republic", Platos' magnum opus.