Put a lot of skim milk in a glass bown and put in microwave on high for 
6 minutes. (A lot is about 1 1/2 or 2 quarts -- it doesn't seem to matter
to the microwave.) I think it is better in a taller vessel, but this might
not matter either. Try it both ways... Then cool to tepid. Meanwhile, get 
out some plain non-fat yogurt (or low fat -- again it doesn't matter, 
except I try to get the kind of yogurt for this first starter that doesn't
have gelatin in it -- read carefully). Mix a little of the cooled milk
into the yogurt to smooth it down (about 1/2 cup of starter yogurt).
THen gradually stir into the cooled milk. Leave overnight in the microwave
or in the oven with the light or pilot light on. Stir if it appear that
nothing is happening. If your spoon is coated, something is happening -- 
it just might take a while to set. When it looks very lightly set, put in 
the refrig. It will be the old fashioned kind of yogurt that Pavel's makes
in the San Francisco Bay Area, but that doesn't travel well at all. It 
separates too easily. But it is wonderful. Use the whey (liquid) in soups
and dips, etc., and the other for spreads or eating or fruit smoothies
in the blender (this morning, I had banana, a whole orange, including the 
peel, some dried apricots, and this yogurt stuff that I poured out of the 
bowl into the blender.) Great and easy!