This FAQ is not designed to give the best path through the game. Its aim is to answer common questions and get people un-stuck. We try to keep these sorted so the most common ones are at the top and the ones you'll need earliest in the game are at the top.
How should I start the game? Use http://card-lords.wikia.com/wiki/Redeemable_codes_(hints), then play explore.
How should I spend gems? See How to use gems.