When I was making my pressure plate, my wire stripper decided to disappear..that's when I discovered this laughably easy technique for stripping wires. It's so easy, that I can't believe that I haven't seen it before. The scissors on my leatherman were perfect for this job, because they could cut through the plastic coating on the wire, but not the metal itself. This same method will work with normal scissors to, as long as you don't use all your strength when cutting.
Step 1: Cut!
Simply act as if you were going to cut the wire in two...but don't. Stop adding pressure when you reach the wire, and spin the wire around. You want the blades of your scissors to have touched the wire all the way around. When you're done with that, the plastic will just be indented all the way around. Next, give it a few bends...the plastic will easily split, revealing the metal.
Step 2: Finish Up
Once the wire is exposed all the way around, you can just pull the plastic off with your fingers. If you cut too far in, you may have to use pliers (or teeth, in a pinch) to get it off, but fear not, it will come off quite easily with such implements. Automatic wire strippers are favorable to this, but if they decide to disappear on you, like they did to me, you'll be OK now that you know this little trick!