Small faces usually require small frame sized when you buy prescription glasses. If you a female, you may try cat eye style glasses frames that look great for small faces. If you a men, maybe you can try small round glasses or some small sized wayfarer style glasses. Anyway, to get the best looking glasses frames, you'd better try on some glasses frames that ranges in different style to see what style of glasses is the best suitable one. Good luck.
As far as I'm concerned, people with small face are easier to find a suitable glasses, for they look beautiful on various styles of glasses. In terms of your problem, I think you'd better choose small framed spectacles, for large framed eyeglasses would make their faces look smaller. What's more, they are suggested to choose rectangular specs which would make their faces look wider and more modeling. The most concrete suggestion is that try more glasses on you in solid shops to look for what kind of glasses fit you well. As long as you make proper matches, your requirements would no longer be a problem that is hard to solve.
If you have a small face, glasses frames in small size would meet your needs. So you shoud go to your optometrist who will measure your size for your glasses frames and lenses. Then you can choose the style of glasses frame you like best and lenses you want to get. And the optician will ask the lab technician to make glasses that are customized to fit your small face properly.