A round face has no angles so you have to be extra careful while choosing a frame. Pick the ones that make your face look longer or slimmer.
Best Frames: Go for square or rectangular frames (wider than your face); wayfarers are the safest bet as they draw attention to the top of the face.
Frames not for you: A strict no-no to round frames (you already have a round face!), smallish frames, or even large frames because they won't do anything to improve your face's round contours.