Acquire yogurt culture. You can buy powdered culture, but most people just buy a small carton of plain yogurt at the store. I have found my very favorite yogurt for starting a batch is Dannon. Be sure to save ½ C of your yogurt to be the base for your next batch. If you forget or it goes bad before you are ready to make your next batch, just start again with store-bought! Heat milk to 185° in a heavy bottomed pot, stirring with a whisk the whole time to keep it from burning. I put mine on high heat so it heats up faster (5-7 minutes) If you are uncomfortable with using high heat, by all means, use lower heat, but you will have to stand there stirring longer. You can use any kind of milk whole, non-fat or anywhere in between, *but not ultra-pasteurized. Apparently, the ultra-pasteurization process, in addition to making it taste weird, kills everything in it. Since yogurt requires bacterial action, U-P milk just won’t work. When milk reaches 185°, remove from heat and pour into room temperature crock pot. Remove yogurt from fridge and leave on counter to warm up. When milk cools down to between 110 and 90 degrees, whisk culture into warmed milk. Depending on the temperature of your room, this can take an hour to an hour and a half. Cover and wrap in insulated bag or towels. Let sit at least 8 hours. The longer you let it sit, the firmer it will be. I have let mine sit for up to 18 hours. You will see the cream layer on your yogurt if you use whole milk unless it has been homogenized. A half gallon of milk will yield approximately the same amount of yogurt. If you see some yellow water-y looking stuff floating on top of your yogurt this is perfectly normal. I use a big spoon to scoop it out, as I like my yogurt a little thicker. You can stir it in if you want. If you want your yogurt even thicker, many people add a little powdered milk to theirs, though I never have. On rare occasion, I strain mine through some cheese cloth or coffee filters to make it extra thick, but I feel like it wastes a lot of yogurt to do this (reduces the volume by more than half) so while it’s delicious, I save that for special occasions. Occasionally I have had the milk not set. Perhaps the yogurt was added when the milk was too warm, or maybe the culture was bad. Once, I had it turn out pink! In either of these cases, (especially the pink one) it’s best to throw it out and start again. That said, I’ve only had those results maybe three times in the years I’ve been making my own yogurt.