I DID NOT MAKE THIS, so all credit goes to the original author, Mr. David Creamer, it's a very excellent, easy-to-understand guide to the general typography rules as well as a guide to what all the stuff in Photoshop's Character box does. I've been skimming through it and found it to be a good refresher even for myself, so I hope it helps others as well.
Again, it's not mine, just passing it along...
