I know this seems like the easiest hair dye project out there.. but my question is about base colors and levels...

My friend has light brown/golden hair with highlights and she wants a darker brown. She had it dyed and it wasn't dark enough for her, and it faded pretty fast. My other friend had this same situation a few months back and I dyed her hair a darker brown for her. It didn't turn out as dark as we hoped (I only used a 10 or 20 volume developer, which may have been the problem?), but she was happy. It faded just as fast though.

So my question is.. if she dyes her hair at home (she asked me to help her although I think she changed her mind, I'd like to have some knowledge on it anyway), should she dye a shade or two darker than what she's aiming for so if it fades it will be about where she wants it? What base color should be used so it doesn't fade to a dull greyish/greenish color? She has a warm skin tone, and light brown eyes. Would a 30 volume developer have a better effect?

She says she wants it my color, which is currently a medium brown/slightly auburn color.

I don't know much about dying light hair because I'm a natural brunette!

If you your friend wants to go from light brown to medium brown, she will need to use a deposit only hair color. Therefore, she should use a 10-Volume Peroxide Developer with a medium brown hair color, which is a level 5.

Wouldn't a higher level volume create a bigger change in hair color? Or does that only count when lightening hair? I guess I've never really understood levels, but I thought a 10 volume would darken/lighten by one shade, 20 by 2 shades, and 30 by 3 shades... is this wrong? And I think she wants a level 4 shade... so would I go with a level 3 so when it fades she'll get the color she wants.. or will it just shade to an ashy/grey tone if I do that? It's been bleached, so it will inevitably fade..

Sweetie, if your friend wants to go darker, she you would have to use a 10-Volume Peroxide Developer with the selected hair color. A 10-Volume Peroxide does not lift or lighten hair color, it only deposits color. Most at-home hair color contains their own Volume Peroxide Developer. She can get a separate hair color and developer at a beauty supply store, or she can choose an at-home hair color. Medium brown is a level 5, and dark brown is a level 3. If she wants the hair color you have, then she should go with the medium brown color, but if she wants to have dark brown hair, she will need to choose a dark brown color.