Add your culture to your warmed milk- if its powdered, sprinkle on top and let sit 5 minutes before stirring in. If its whey, just stir it in.
Put your rennet into the water to dilute it, then pour it into the milk and stir well. Its okay if you accidentally get 3 or 4 drops of rennet, but go slow and try to get it as close as possible.
Cover your milk and let it sit around 12 hours, or overnight. I usually average 14 hrs by the time I get around to dealing with it the next morning.
Cut your curds in a 1 inch grid- to do so, cut one inch strips in one direction, then the other to make an approximate grid. Let it sit a couple minutes, and get your cheese cloth ready.
I prefer to use cotton muslin fabric, actual cheesecloth is awful! You'll need about an 18" square or bigger to strain a gallon of milk. I drape it in a bowl or pot, and then pour the curds into the cheese cloth.
Take the corners and tie it up, then hang the cheese, overtop of the bowl/pot, in whatever fashion you can mcgyver. From a pot rack...from a cupboard knob...on a wooden spoon hung between two cupboard handles.
Let it strain 6-8 hrs. If you're making bigger batches you'll need on the longer side. On the shorter side yields a softer cheese. If you want, you can gently stir the curds within the cloth a couple times, but its not neccessary.
When its done hanging, take the cheesecloth down, dump it into a bowl and stir in your salt. If you're using a premixed seasoning like ranch dip mix, dont add additional salt.
The salt acts as a preservative so unless you plan to use it within a day or two, I highly recommend salting it.
Put it into a container in the fridge, and get excited to use it!