Yogurt is a staple in my Lebanese friends' home. They use no fancy machines. It's very easy and tastes infinitely better than storebought.
Scald the milk. When cool enough to stick your pinky in for 10 seconds without discomfort, add the yogurt and stir just a bit. Put a lid on the pan and wrap it in an afghan, or towel, or something else to help keep it cozy. Put the future yogurt someplace quiet and let it sleep overnight. In the morning: voila! Yogurt! Remember to save the last bit for the next batch.
Important hints: The only thing you need to remember to make it come out right every time is that the yogurt likes to be warm and quiet. Therefore, when you stick your pinky in-if it's comfy for you, it's probably comfy for the yogurt. If you jiggle it while it's trying to sleep, it's going to be ruined. Just be gentle with it.
*If* it screws up, there are two options: one, squeeze a lemon in it, let it wait 8 more hours and see if it recovers. If it doesn't recover or if you feel nervous about having warm milk fermenting for 16 hours or so, salvage the remainder by hanging in it cheesecloth over the sink until it makes "labne", i.e., cream cheese-like stuff.