Firstly, I think big size sunglasses with black frame can fit most people. They are always the first choices of many famous stars in Hollywood.Then, as far as I'm concerned, the choose of sunglasses, in most occasions, depends on the shape of your face.If your face is wide and chubby,big size glasses with wide frame are a good choice. The color of the glasses should be dark, as they can focus others' eyesight on the central part of your face, thus your face will looks more exquisite. As for squared face, big sized sunglasses with wide frame is suitable. Because it can soften the strong and hard impression of squared faces.You see, big sized sunglasses seems to be the first choices. Maybe it can make you more eye-catching.