When she starts to ask you about it. That is a good time to start allowing some things.
Or if you want to make a suggestion like the mascara (good call mom) then you can just say. "That skirt is so cute, how about a sandal with a little heel?"
Make sure she and you always know the dress code, so money is not wasted on the things they do not allow.
The next time she needs a new piece of clothing, give her a budget and let her go and pick it out. You can be there, but really let her decide what style color she wants. Show her how to shop sales how to use coupons. She will become a savvy consumer.
I remember when I our daughter wanted a blue streak in her hair for her 13th birthday gift.. This is a child that never had asked for anything remotely like this before. We looked into the process, the cost, and the fact that once school started, they did not allow "unnatural hair colors" in 8th grade.
It meant stripping her hair, then coloring it.. it cost over $150. + tips. She had saved up money and asked for gift cards to that hair salon.
The stylist reminded her.. "The more you wash the hair, the more you will lose color.The mores time out in direct sunlight, the more it would fade AND swimming in chlorine was really not a great idea unless each time, she really washed her hair. Also the stylist reminded our daughter that her hair grows really fast, so it was going to show roots fairly soon."
Daughter still wanted to do this. She was excited and the other moms were shocked. They could not believe "I had let her do this". I told them, "do not worry, she is soon going to realize this was way too much money and too much care for that streak"..
Sure enough, it became a bit of a burden. She had to wear a sun hat (hello 103 degree bright sunlight!). She planned out how many times in the chlorine..The newness wore out just in time, her her to have to get it back to its natural color. The funny part was when we were up at her school and the Principal saw her hair and said, "what on earth? That is going to be a natural color by the time school starts?" our daughter assured her yes, it would be fine.
Another $200. to get it back to "normal" and she said she would NEVER waste her time or money on anything like that again.. hee, hee. Her friends? None of them ever did it either.
I did send her to a class that was offered at one of the dept stores (some of her friends also went). These beautiful women ran the class and spoke with the girls about proper hygiene, make up, poise, manners, how to walk, how to sit, how to get in and out of a car, what types of clothing looked good on different bodies how to apply for a job and fill out applications!. The girls kind of rolled their eyes talking about it, but I think they each really learned a lot from this class.
Even though we moms had spoken about these things, seeing these glamorous young women speak with them, made an impression.
Just keep the communications open and give her a little freedom. Compliment her for her good choices. Be sympathetic, when it does not end up that great. Be truthful about your own make up, clothing and shoe disasters. She will learn to trust your advice.