As an addendum to this question, my situation is even worse: my character is level 60, and my friend has just begun. This translates in me getting 99.2% of the xp points.

Going to higher level areas would not help, because he would run into the level penalty.

Is there an effective way (strategy/ zone grinding) to help him level up fast without boring him do death? (I'm trying to make him like the game, not hate it)