While doing research for my thesis I happened to come across these fun beauty tips from Jean Harlow upon browsing a vintage press book for her film The Girl from Missouri (1934). You might want to take some of these with a grain of salt, especially the bit regarding her hair and there being no tricks to it. :)
"Personally, I dislike a made-up look. I never wear mascara unless my screen work demands it. I use only powder and lipstick."
"I believe too much make-up is bad for women who prefer a healthy, natural complexion. Every woman knows what make-up she desires, and she should deal with it judiciously."
"Of course, we use different make-up for our screen work than we do in our personal lives. The same thing applies to clothes. Clothes and make-up are always a part of characterization. You must adapt yourself to the character you are portraying on the screen. That is the reason they call us actresses and actors."
"There are no tricks to the care of my hair at all. I use castile soap and shampoo it like everyone else might do. I never use a rinse. I shampoo it every four days, but I rub hot castor oil into my scalp before every shampoo."
"Do the studio lights damage it? Well, they dry it. Also, I'm always getting powder in my hair from my make-up. I never wear a hat, you know, and the sun burns my hair and turns it yellow. I don't mind that because I hate hats."