Most Helpful Girl
Haha this is a bit cheesy no offence. I mean sure she would be flattered but if her eyes are as gorgeous as you claim she might have herd it a couple other times from other people, maybe to a point of it being annoying.
Besides women like men like to be complimented on stuff they have earned. Maybe she is really smart but no one has acknowledged it, then compliment her on her smarts, or maybe she has a wicked sense of style or a sensible yet zesty style where she adds hints of color or pattern compliment her on that. Or you can compliment a small detail that no one has noticed before and she will see that you have a good eye for detail and can pay attention.