I am a male in my 30’s, and boy do I wish everyday to see a girl in short shorts with sheer Pantyhose (like the Hooters girls and cheerleaders)- and garter belt and stockings are of course an eye catcher.
-So, my quick answer for a 12 yr. old girl to wear?- is “NO!”
-but after thinking… If she wants to wear coloured and/or designed Pantyhose under her shorts- that seems okay. Most Men are very attracted to the shiny suntan/nude and black colours. (they are made to look and feel *alluring*). The bright coloured ones may be seen by the girls as a way of standing out. (and they are warmer!)
– as for the garter belt and stockings- does she see this as a “I look sexy” thing? or does she want to be more ‘lady-like’ and feminine and/or old fashioned/retro? If she were wearing a skirt/dress that was long enough I would say ‘ok’. If she were doing this to show off – “NO WAY!”
If this is a real question

A 12 year old should be a child for just a little longer. The whole garter belt/pantyhose thing is just an attempt to fit in with the crowd that wants to appear “grown up.” If you are caving in to the social pressures that she feels, you may as well take her to family planning now and get her on the pill because worse things are in store for her if she hasn’t learned morality and disciplin by now.
If you don’t mind her getting attention (possibly perverted) from 30yr old men, then sure…..