I make yoghurt in my crockpot and I use half and half. Heat the liquid to 180 degrees, cool to 110 degrees, stir in the starter (abt. half a cup from the last batch) cover and wrap well (I use 3 large towels) and let stand for 8-9 hours. That seems to be the right amount of tartness for us. Then strain using coffee filters in a colander.
The whey can be added to soup stock for more protein. It can also be frozen.