Bleaching roots? (read more!)?

So I have naturally black hair. I bleached my hair so I could dye it pink and it worked suprisingly! Anyway, roots are horrible and I'm sure i'm gonna have to bleach them again to get the same color....If I keep this up, will it ruin my hair? Just bleaching my roots though? and then dying them pink? (or pretty much, what would be the best way to go about keeping up with this hair color??) Also, what are some good after care treatments and shampoos and stuff I should use? Any help would be appreciated! thanks :)