Behind my ears is my hardest spot. I also have a scar that is slightly raised which the razor seems to snag on. I'm still new to this but working on it, have gotten better just from watching videos on you tube. I don't shave the top off my head since there is no hair there, but I ran the razor across last shave and it seems as though my head isn't all that round! Will pay more attention this Saturday. I can get a BBS fairly easy since there is not much there to start with.