Making a yeast starter is pretty simple. Boil some water, add some Dry Malt Extract (about 1 half cup), cool the mixture to about 70 degrees and then add the yeast.
One issue I've run across is having a stable environment to let the yeast do its thing. I imagine large fluctuations in the temp stress the yeast. Too cold, no propagation, too hot, probably dead yeast all together.
So, I found the perfect environment, the oven light provides just enough heat. It's almost 80 degrees, which may be a little hot but I'm just trying to create lots of yeast cells, not ferment beer.
So, there you have it, the oven light.
-Andy