You don't want to let your hair grow too long if you have a long face shape. Why? It makes your long face look EXTRA long. Consider a shoulder-length hairstyle, such as this one on actress Asia Argento.
If you want long hair, cut in long layers. The shortest layer should hit at your chin.
See more shoulder-length hairstyles Wear glasses? Find out which frames flatter your long face shape in Best Glasses for Your Face Shape.
Find out what face shape you really have.