I have a weird kind of question. I think.

I'm having trouble keeping up consistency when I crop faces for icons. I usually try to notice subtle things when I cut them off-- where it is on the hairline, is there a pattern in their shirt showing or not showing, etc etc. I was wondering if anyone else had a better, more precise method to cropping? Also, I don't like to get a lot of the "background" in my icons. Like in this one, you can see part of another actor's shirt in the background. Just kinda throws it off for me.

Any suggestions, or does it just boil down to being meticulous and attentive? (I have PS CS3, if that makes any difference.)