The Four Factors
KJ's original "Tempo-Free Stats for Dummies" from the precursor blog to The Only Colors.
To me, "A Starting Point For Analyzing Basketball Statistics" is quite thorough and has a ton of great information. It is, however, pretty academic.
Dean Oliver's own explanation of his Four Factors. The formatting is rough to try to read, but it's a great explanation. This short article completely changed the way I think about basketball.
KenPom's original entry on the Four Factors and also his "Help" page are both helpful.
If you're looking for more, my best suggestion is to buy Dean Oliver's Basketball on Paper which basically began the world of basketball analytics as we know them.
If you're into this sort of thing. At TOC we probably won't use plus-minus much but the best primer is here.
Plus-minus is used more in the NBA for data reasons, but I introduced them for college here.
For what it's worth, here's KenPom's take on plus-minus.
A way to measure offense-only contributions. Here's KJ's explanation.