Hi Pam,
I really suggest spending time reading through the forum. Read threads about the cheeses you know and like. In there you will find all sorts of tips and tricks.
The "mulitply by 3" to determine the set time, for example, is about using a flocculation multiplier to determine how long to wait after adding the rennet before you cut the curds. It's not hard to do. Take a small plasitc bowl (like a small snack bowl that you might put a handful of nuts in, or what you might store an infants food in), sterilize it, and float it in the milk just after stirring in the rennet. If you give it a tap, it will sail around the milk. Write down the time you added the rennet (exactly, including seconds; I always add my rennt at the 00 second mark). For this example, let's say we added our rennet at 12:00:00 exactly. Now, every two minutes, give the bowl a gentle tap on the side, and after awhile (approaching 10 minutes) you will notice it doesn't move as freely. As if it's moving through thick swampy water. Now tap every minute and as the bowl moves less and less, increase your testing to every 30 or even 15 seconds. Eventually, it will reach the point where a gentle tap won't move the bowl out of it's place. It will just lurch forward and get sucked back, like a cartoon character with their feet in ACME's glue. That is the point where the milk "gelled", and is the floculation point. Write down the time (12:12:30). Figure out how much time has passed since you added the rennet, which in our case would be 12 minutes and 30 seconds (you usually want this to be in the 10 to 15 minute range).
Take your 12 minutes and 30 seconds and multiple it by 3 (in this case, some cheeses use a bigger mutiplier, some use smaller: bigger = moister cheese usually), which gives you 37 minutes and 30 second. Now, add that amount of time to your rennet time, so we're now talking 12:37:30. That is the time you cut your curds. You do not test for a clean break, you just cut them.
There are lots of threads explaining why one would do this, and how, so as you read around you will learn all sorts of neat stuff.
- Jeff