The eyebrow to lip rule is what we implement when people come in to rent skis. Reason being that if you're renting your skis, you're usually not that good. And if you are good, you'll know what size you want. That being said, if you're any good at skiing you should shoot for skis at eyebrow and above. For example, I have a pair of 181s and 185s. I'm 5'11"ish, so the 181s are pretty much exactly as tall as I am and the 185s are taller. If you're 5'9", 178s are perfect.