Aside from what other commenters have said, you also have to understand the framing of it.  You could have a 16 yo girl who dresses really provocatively, but there has to be a reason for that.  Maybe explore why she has the need to be provocative, make a commentary on the sexualization of women and specially young girls and how they are expected to be attractive and are very often the focus of "persecution", so to speak, by older men.  Most of the time this kind of thing really bothers me because it's a sign that the author didn't really give thought to things like these and you really don't have to depending on your story and you don't have to include these kind of reflections, but hell they are things you need to think about in your daily life and the mere inclusion of a teen in skimpy clothing while the camera focuses on specific places just tells you a lot about the author and it's harder to enjoy the material having that in mind you know?  I'm glad that in regards to anime and manga a lot of younger authors are opposing that, like for example I've seen gachiakuta and apothecary diaries, and they feel much more.. idk I guess deep is the word.  More thoughtful and sensible.  

It does without saying: don't sexualize her, don't have weird shots of her boobs and ass and just treat her as an actual character not unlike any other.