Chazal were concerned about certain Jewelry that a lady might be tempted to remove in the street to show her friends. A brooch is such an item. However, if the pin doubles as a fastener for her blouse – there is no concern since it would be immodest. (ShA9)
You can pin clothing together and wear the pins outside on Shabbos. Any unnecessary pins are massui. (MB 24)
A wad of cotton placed in the ear to drain pus should not be worn out in the street – it could fall out and you will be tempted to carry it. (ShA 15 – MB 40)
An orthotic in a shoe is no problem even if not attached. However, in a slipper that isn’t closed all around, the orthotic must be attached before wearing it outside. (ShA 15 – MB 44)
You aren’t allowed to put pepper in your mouth on Shabbos as a remedy for bad breath. The same goes for a chunk of salt for a toothache. (MB 49)
A person is allowed to take off and put on what he is wearing in reshus horabim as long as he doesn’t carry it. (ShA 16)
Nowadays, women customarily wear Jewelry out on Shabbos. Even though the main halacha is to forbid this even in a courtyard without an eruv, The Shulchan Aruch and Rama themselves justify these ladies and we may not protest against them. (ShA 18 – BeH “ki”)
A woman is forbidden to make-up her face because of the melacha of dyeing. The same goes for eye shadow. Greasing hair is forbidden because of the melacha of smoothing. It is fitting to warn the family about this. (ShA 25 – MB 81)
No braiding (or unbraiding) hair on Shabbos. The gemara says it is too similar to building. And when it is a wig, it’s the melacha of weaving. Do not protest in places where they won’t listen to us. (ShA 26 – MB 82)
Don’t part your hair with a tool, but with your fingers it’s okay. Even if a hair pulls out, you don’t have intention for that. (Rama 26 – MB 84)
Don’t use a comb for your hair at all. You may use a soft brush just to put your hair in order. Even so, the minhag is to have a separate Shabbos hair brush because of uvdin d’chol. (ShA 27 – MB 87)
You are allowed to rub your hair with your hand. You may also scratch with your nails and part your hair with your fingers. (Rama 27 – MB 88)