I try to look at her as an overall picture to get her personality. Does she look sporty, or gothic? I try to get as much info without talking to her. But, I look at her hair mostly if it's different...it's not intentional but I seem to be drawn to dark hair more. I like blondes...and all, but dark hair always catches my eye and Latinas for some reason it's not that I look for them I just notice them more.
I don't look at individual body parts like thighs touching, ankles, calves, eyelashes, eyebrows, purse or shoes couldn't care less about those things. Just overall body if she looks like healthy weight then it's all good.
If it's a girl I REALLY like, for instance a few years ago this short girl with black hair...go figure right? I make it known that I'm paying attention to things she changes about her appearance. I want her to know that I'm noticing the little things.
I look at the nails and hair, not really too much the shoes unless it's a dress up party or whatnot.
Speaking of hair.. WOW I was in the food store yesterday and this girl had curly hair and she stood out from half way across the store.. In that case yes I checked her hair and face out and her legs all in once glance.
If it's something quick like that then I don't make many judgements but if I see the person more then once then I can start figuring out stuff.
They notice the overall effect, but most probably can't pinpoint why one girl looks stunning and another merely pretty if the differences involve the little things like eyebrows, skin care, hair, flattering style, proper use of makeup, etc. Small things can make a big difference even if individually they seem inconsequential and "invisible".
How irritating is it when guys say women have it easier? Look at the sh*t we have to deal with looking pretty and sh*t.