It's worth noting that heroes can only learn their specialty skills above 3. What I mean by that is, an attack hero cannot learn a defense skill to 3 or higher, it caps off at level 2. Try to match up what the book recommends, and what type of hero you're teaching it to.
Of course, until you start getting purple heroes it really doesn't matter at all, but once you do keep that in mind, okay?
Also never learn counterattack, its terribad.