Originally Posted by
BuffCyclist
Two words: mirror.
Oh wait, that was one. LOL
I just use a handheld mirror, turn my back towards the sink/bathroom-mirror and hold the mirror up to look back there. Well, I actually do it all blind (without glasses) and then once I'm done, I use the mirror and look it over. Its really a lot easier than you'd think. Just go slowly, and once you get a majority of it done, you can hear the difference in the trimmer between cutting hair and not. I run the trimmer over my entire head pretty quickly, then once I get a majority, I go back and go slower, really paying attention to how far I'm moving the trimmer. Lots of criss cross patterns (forehead to back of head, back of head to forehead, right ear to left ear, left ear to right ear, etc) and you won't miss any spots. Then all you have to do is look at it when you're finished.
Where I really have trouble is my neckline. My hair grows down my neck quite a ways, so I just use my electric razor ( 3 circular blades style, for face) and shave that up for a while. Its hard to shave off too much that way and I get a nice clean neck line every time.