I have a serious problem with cutting long layers..everytime i cut the back behind the ears and beginning of lower neck line, I get a huge hole...from the side view...you see a diagonal line from the bang to the ear..then a huge hole...then the nape.  What am I doing wrong??  Am I suppose to take my diagonal line from the front all the way back or do I stop before the ear??  If I stop before the ear..How do I connect my layers from the front to the back...? Do I start cutting layers from the back or from the front?

When I start from the front I get lots of layers in the back but i wanted short in the front and long in the back. when I start from the back..I get long in the back and long in the front.  But I want short layers in the front...any help or advice.  thanks.  I have books and videos...but they do not show particularly the joining of the front side to the back side. 

The thing to remember is there is no hair from the ears down to the nape on the sides of the head, so sometimes you have to adjust the finger angle to make sure the interior and exterior guides meet and are where they should be.

Also there is a technique that many people teach called Volumetric or horizontal layers but this technique is not that good for longer hair than the top of the shoulders. Vertical sectioning sometimes is best for longer layers because it is easier to adjust the finger angle when using this technique