Dark hair?

I know that certain types of vinegar are supposed to subtly lighten your hair. Are there any ways (besides hair dye) to make hair appear darker? My hair is naturally a very dark brown. I put purple streaks in it a few months ago, but those faded to a red/orange color. Then I went and dyed it with my natural hair color dye. But that is fading and the red is starting to show again. so yeah. suggestions please?