OK, so everyone has a tube of black mascara. Some of us even have tubes of exotic colors like purple and green but if you're over 29, they really shouldn't be worn unless it's Halloween or Disco Night. A lot of beauty experts say to use two coats of black for night events. This is not necessary either.
Another coat just on the tips of your lashes will give you all the drama without creating the shadows in makeup fashion that age eyes in any light. I hate black mascara. Partly because everyone thinks they need to wear it and partly because nothing ages you faster than lashes that look like furry caterpillars on your face. The only women who should be wearing black mascara are women with NATURALLY black hair. No one else. Black is the color most heavily photographed and advertised because it shows up on film. That does NOT mean it's the most appropriate shade for you unless you qualify under the stipulation above. I know, I know, your mom used it, your junior high friends used it, all the girls at high school had some weird competition to see who could slather the most of that goop on and still look awake. Bleah, I say.
So what are you supposed to wear if not black?
Brown hair of any shade should wear brown/black mascara in makeup fashion. No darker. You are not a drag queen (most likely) and a certain level of "natural" is expected and encouraged in the workplace and out.