i guess the worst thing you can do is trying to sing like some one else. apart form the fact that this certain someone might be singing in registers that are simply too high or too deep for your voice, and therefore ruining it, it will ake you just a thin copy.

You see - what made those dudes famous was that they used their own voice, and not mimicing someone else. this is extremely important when singing, for everyone´s voice sounds pretty different. its not like on a guitar, or a piano where they all sound more or less the same.
Its as if you would try to play contrabass with a violin or vice versa. just be yourself.