For a romantic feel go for the midi length or full length as at Chloe and Tommy Hilfiger...

Chloe
Tommy Hilfiger
Or for a more flirty approach take the hem higher as at Derek Lam; but not too high or you will be verging on netball/tennis skirt territory, and frankly that is only acceptable on athletes and school girls.
Derek Lam
Be sure to keep the top half young, not too fussy, and preferably slim fitting in order to avoid grandma chic.
...And here are some Charity Shop Chic beauties I picked up and reinvented in my own way...
Leotard: Primark
Skirt (altered): Charity Shop
Belt: Charity Shop
Heels: Primark
Lipstick: Collection 2000 Mudslide
Leotard: Primark
Skirt (altered): Charity Shop
Belt: Charity Shop
Clutch: Primark
Lipstick: Collection 2000 Mudslide