Cams for Dummies ??

I would like to understand how to pick a cam, and how all the other factors affect selecting the right cam. I'm not an idiot but just reading what I can find here it's like the harder I try to get it the less it all makes sense.

Is there a good book, website, or tutorial I can use to get a handle on this?

TIA!
Nope, 'cause whatever You watch/read/hear, somebody will tell You why it's all wrong...