Cutting skins is pretty easy. The best way and quickest way to do it is with the G3 Trim Tool
. Inexpensive. You can probably pick this up at any mountain shop that sells G3 product. Just put the skin on nice and tight. Run the guide along the ski edge and trim it. Takes just a few minutes. I think I spent less than ten on my last set of skins.
The other thing that works good is a letter opener. Which Voile and others include as a trim tool.