I use an electric smoker for some stuff (particularly doing a bunch of chickens at one time) and have learned two things.
1) If your unit does not have one, go get a heating element with a variable control. They are not expensive and will more than pay for themselves in the meat you don't mess up. Most of those smokers all have interchangable elements.
2) Get a good oven thermometer. A stick in dial type is fine, but if you can get one, those digital ones with the readouts remotely attached to a wire (and you really look like you know what you are doing when you use one
3) Get an oven temp therm to keep all of this under control. A cheap one that just sits or hangs on the grill screen works great (although your smoker may already have one)
Temperature control, my friend. That is the key to happiness in elctric smoking.