Your glasses need to be some that fit your look the better, but what counts the most for a woman is the attitude, also the care that you have with your skin, hair, you must be clean, smell good, well, take care of your body and look. You should also study body language, learn how to use your voice. So it's not about looking pretty, it's about looking good. First of all you have to remember that glasses are a matter of necessity, so it's not like women will judge you bad for using them, most of them even find it sexy, if you use the right glasses.
It depends on the face shape and facial features of the guy. Also, on the frames and whether on]r not it's compatible with the guy's face. But hey, if your ex thinks you're cute in glasses, you might really be. For me, I love the whole guys wearing glasses thing, especially when they don't wear them often. It's like seeing a dorkier side of a guy (depending on the frames) which is absolutely adorable.