Step 6: And NOW: the BACK of the head!
Actually, it's not as hard as it sounds. It's just like cutting the hair on top of your head, you're combing the hair through your fingers to get the length by feel, and then cutting away any hair that's past the hand, again by feel. Work your way from the top of your head toward the back of the neck. Make the hair at the very back of your head a little longer, so that the shape of the head looks full and round back there, but as you get toward your shirt collar area, the hair should be getting very short (the hand-comb should be very close to the head, so the hair is just a finger's-width long).
Once you've cut the hair at the very back, cut the hair on the back left and back right of the head, working your way from the top of your head down to the collar. Usually, I have pretty much already cut this area, when I tilted my head and cut the hair on the sides, but it's good to make sure that the hair all around the back of the head is cut.