Hi, I'm a girl and I know this situation all too well...
If everyone is constantly saying that she is pretty, don't. She will think you're just like all the other guys who were looking for just a physical relationship. If you compliment her appearance, definitely make sure you have already complimented her interests/sensibilities/culture/intellect first. She isn't an airhead and if she really does get complimented on her looks this often, she probably sometimes feels like everyone sees her in the airhead light.
This may seem a little tacky but you may want to check out a certain scene in Spanglish, where Flor tells Mr. Clasky she enjoyed watching him cook (because he is skillfull) and he says, "If it's anything at your end, imagine what it is over here...but the last thing you want is someone going off on your looks...it's just that you are drop dead crazy gorgeous!" *Paz Vega's character, with or without intention, gave Adam Sandler's character a perfect opportunity to compliment her physically...you don't want to go right into it with a girl who's heard it a million times. Otherwise it's just old news!
Usually the "corny lines" only work in EXTREME moderation...in other words, don't use this approach more than once in one day because it would seem as though you were trying too hard but had no real substance or stuff to say. Corny lines can be dangerous because there is a fine line between them and pickup lines, and a girl who is genuinely interested in you will not be interested in past approaches to pick up other girls! Most importantly, never use the same line twice!
Eye compliments can come off as a little corny but if you say her eye color is cool or something (or take notice of the color pattern in her iris) that's totally different and she'll like it...it also says that you see her as an intellectual (who just happens to be very pretty lol) I like the iris pattern one. But the absolute best eye compliment you can give a girl is just really good eye contact!
But it's really cool that you're concerned about this because most people wouldn't be. :)
mate, that's corny lol but sweet because ur making the effort, why don't you make her know your paying attention to her, by maybe describing her eyes to her or her lips or her hair or something eg. ermmmm, "i noticed that your have a slight shade of blue in your eyes,(she says reaaly? lol), then you say yeh..i also noticed that when you face the light, they glisten a green I can't describe, but when you look right at me...they are a colour so perfect I don't see any colours I just see you" lol I would melt if a y sed that to me lol you could downply it but I think this is sweet :)
One time I had a guy tell me that me eyes reminded him of swimming in North Carolina. I thought that was really cute because he said that and I was like what and he said '' I wanna go swimming in your eyes." I just thought that was really cute.
I'm not sure about the flip side but beautiful seems overtly cliché. I would say something like stunning or radiating. But when girls compliment my eyes they say sexy or gorgeous. Had one tell me they make her w$t. It's all about the gaze, not to get confused with staring, gazing is totally less creepy like. Plus it helps to have nice eyes which I have been blessed with.
i would say: is your father a thief her : no me: yes he is!!!(give serious look) her : I think your crazy, goshhhh no!!!(by now she'll give a grumpy look) but don't worry!!! give a grin, and say... me : yes, he is... he stole the stars and put them in your eye's!!! :) lol