Tips or a guide for not-always-obvious aspects of build effectiveness anyone?

tinythinker

There are things about build and gear choices which can be easily missed or under-appreciated, such as how spell effectiveness (healing or damage done) is tied to how much magicka you have.

Some features on armor, like impenetrable, can be overlooked or not well-understood because it isn't clear to the casual observer what exactly 40, 60, or 80 extra critical resistance means (one source I read said every 10 points of critical resist = reducing an enemy's critical chance against you by1%).

What tips, advice, or planning suggestions would you give to those players who don't know many of these ins-and-outs? What would be most important for them to know (or maybe what important thing would they be least likely to know)?