If you have a long face, you'd better choose one to cover as much of the center of the face as possible. I think the round and big sunglasses will suit for your face. What you should remember is avoiding sunglasses with heavy nose bridges , bold colors and square shapes.
From what you have described, I know that you are upset about what you wear in order to appear more attractive. So, here I would like to tell you that, wayfare sunglasses or aviator sunglasses could be suitable for you, which would hide those defects. Since your skin tone is great, there would simply be no other problems, just head to a local optical store and pick up a nice pair of sunglasses.
People should choose the suitable style and color according to the different hair, face and skin. If you have a long face, you should try to minimize the impact and make your face look shorter. Don't choose sunglasses with very narrow lenses. Recommend you to choose lens with bigger diameter, round shaped. Quadrate lens is suitable for round face. Big lens is the trend nowadays. It should be better. If your skin is fine, you can choose color of lense according to your preference and skin color. Brown and grey colors are very good choices, because they could provide 100% protection from the UV rays, and they are also very fashionable. Hope it is helpful.