I am struggling with the neck area too. Though, I have only tried my neck 2 times now. I just shaved my beard off Tuesday I believe it was. I have only been shaving every other day. It was better the second time but I just couldn't get a decent grip. When I got my neck stretched out right. I couldn't see. If I can't see I don't know where to stop.
If I can see I cut myself because the skin isn't tight enough or has an odd curve to it. All my neck hair grows towards my right ear.