Tyler G.,
Welcome to the forum!
Some good reference books might be at your local library. Yes some might be dated but the basics are there.
Here in NJ and 72W Ku (AMC6) is the most Southern satellite, probably is for you also. There are 4 NBC MUX channels there, which are on most of the time, and over here the signal quality's about 70% with a clear path to the satellite using a 39 inch dish and an Amiko STB. If you are getting 50 - 60% signal quality but your picture is in the clear don't worry that much about the % quality. Here some stations come in with 45% quality but they are fine.
Signal quality is affected by a myriad of factors such as dish size, obstructions to the path of the satellite, geographical location, length of the coax run, dish quality, the satellite's footprint, rain. Some of these factors you can control, others not. Also, on the same satellite you'll notice that some transponders have a better % signal quality than others. Moving the dish to different locations on the property can have an effect too. That is something you can control.
In my experience not all FTA receivers are the same in measuring signal quality. Oh, and when heavy rains occur you might experience rain fade, it happens to all of us.
Have fun with FTA.