Place a wire mesh strainer or rice strainer over a bowl, place a double layer of cheese cloth, or a basket style coffee filter in the strainer.
Add yogurt. Cover with plastic wrap or foil, and put in the fridge.
Drain for 1 hour to remove 20% of the whey.
Drain for 3-4 hours to remove 1/2 the whey.
Drain overnight (about 8 hours) to remove all the liquid, this gives you a consistency of sour cream.