If you have a young looking body than I don't think there is a problem wearing that kind of clothing.
I agree with you women SHOULD be able to wear sexy clothing at ANY age =)
You should really be asking women. Guys don't know what womens clothes are called, but I will give it a stab.
Just wear clothes that you see other respectable attractive women wearing. Ask them where they got the jeans, or shirt or whatever. That's what every other woman seems to do. Men usually like clothes that accentuate your figure, not conceal it. You don't have to (nor should you) go overboard with it, just keep in mind whether whatever you are wearing hides you or displays you.
Remember also that guys don't scrutinize your clothes or makeup or hair like women will (unless you really go wild or really look like a mess).