Here are some excellent online user guides from West System epoxy:
And here's a link to EPOXYWORKS magazine:
Although there are (slightly) cheaper epoxies than West, I've stuck with them for 20 years or more simply because they really are a class act. Their R&D is superb, and you can call them on the phone with just about any harebrained question and they'll patiently do their best to answer it (or tell you if they don't know).
I have no financial connection to them but they're a good outfit.