He should read Theory of Poker and Small Stakes Hold 'em. Explain to him that "Small Stakes" is anything from $20-$40 down. When he's through with those and if he continues to play the higher low-limit games, tell him about Hold 'em Poker for Advanced Players. Those are easily the three best poker books out there, so you can always use that as good solid general advice.
Barron Vangor Toth
www.BarronVangorToth.com