According to your description, you must be a beautiful girls. If you want to look cool, you can try a pair of black aviator sunglasses. If you want to look sweet and nice, you can try a pair of big oval sunglasses with candy colored frames. If you want to be noble, you can try retro vintage sunglasses such as cat eye sunglasses, or wayfarer sunglasses etc.
Since you have the long and skinny face, you may look serious. So I think the sunglasses with round lenses may suit you. Adding the round shape on your face may bring the lovely sense to you. At the same time, the sunglasses with big round lenses are popular this year which look so fashionable.