A heart face is widest at the forehead, then gradually thins all the way to chin. Best suited to wider frames or ones with an exaggerated brow. Try out the Helio, Callisto or Juno frames.
An oval face is quite balanced, and will luckily look great in most frames. The choice is yours, but particularly look out for the Asteri, Nova, Halley and Zenith frames.
A round face is characterised by rounded cheeks and chin. It's perfectly complimented by a set of rounded frames. The Lennox, Vega and Halley styles are a must for this face shape.
A square face's height is almost matched by its width. You can get away with most frames, but look to maintain an angular style with the Callisto, Juno and Asteri.