Portrait Attempt

I feel like since I have been going to classes (at Art Pad) my drawing has got a lot better, but I still really struggle with faces! I think it's because it's very easy to get maybe one line in the wrong place and then it looks like someone else entirely. This was supposed to be Jack White from his new album sleeve :-/

We think it actually looks more like either Michael Jackson or Prince. When I held it up from across the room, the lovely other half thought it was supposed to be PJ Harvey :-S