What sort of clothing style would be considered "too young" or teenager like for a woman this age? Lets say she is thin with a young face. Can she wear high waist shorts, tank tops, maxi skirts, maxi dresses, tights, leotards? Can she still dress youthful or is that more for early twenties or teens?
You can dress however you like. People complain about high waisted shorts but those can look good even with the right fit and styling. I would say that anything too young would be neons. If you can pull it off, by all means do it, but I can't imagine neons on anyone older than 25. Neon nail polish is a different matter. But you're still young! You can dress youthful with maxi skirts, tank tops, tights, whatever. It's no big deal. But you also get to play it up with being able to dress older such as pencil skirts and more structured blazers with classy necklaces (pearls, etc). You get to do whatever so long as you do it with confidence!
You can wear clothing that accentuates whatever assets you have. If you have a nice ass, then wear yoga pants. If you have great tits, wear a push up bra. If you have greats legs, wear a mini skirt and heels. If you have all of these, send me a message sometime, haha. Jokes.
I've never been a fan of high-waisted shorts on any girl so stay away from those. Don't wear uggs. I've always found tights to be really tacky on girls. Same with leggings. Blouses look really nice and may be something you might want to consider. Other than that, go with what feels natural and comfortable.