Both are good suggestions. But if you've got a bunch of cards to spare, here's some advice Prof. Underwood gave me:
Build five decks. Once they beat one, move them up to the next level. Each deck teaches an important concept in Redemption
1.) No special abilities, or only ones that influence numbers.
2.) All initiative and battle winners. All of a sudden, numbers don't look so good.
3.) FBTN and negate.
4.) Basic theme deck
5.)
Beat them mercilessly over and over again with your own perfectly refined deck