I'm sure this has been done before, but lets give it another go.
Which actress of every one available, living or dead, would you most like to look like? Who has 'the look' that you would strive for if genetics didn't get in the way?
My 'ideal' has always been Audrey Hepburn. Check out the photo gallery pages here if you aren't familiar with her simple beauty and elegance. It wasn't just physical. She had a presence and energy that can't be matched.
http://www.audreyhepburn.com/ or the wikipedia entry here: http://en.wikipedia.org/wiki/Audrey_Hepburn
Or rent "Breakfast at Tiffanys". *sigh*
And she kept her beauty for every day of her life...