If your economic condition is allowed, you can take the big brand sunglasses into consideration, like the Oakley, Adidad and so on. If not, you can also choose the good ones with common brand. You have the square jaw which may show a little crudenes. You may choose the sunglasss with round lenses to coordinate with your face shape to make it look nice.
Well, it is really important to choose the right frame for each face shape. In your description, you have the square face. For square faces the goal is not to find hard angular lines that will accentuate your strong features, but to soften them with oval or round frames. So I think you can just wear the sunglasses which have the oval or round frames. Besides, except for the frames, you should pay more attention to the color of the sunglasses too. Anyway, just go to the store, there are professional persons who can give you perfect advices depending on your own condition and your needs.