Most ppl that wipe off their trading accounts are leaving the scene not because the lack of technical knowledge, but because of their inability to control themselves. Mostly psychology is the key that separates 20% (maybe less) of succesful traders from 80% of loosers.
The Disciplined Trader by Mark Douglas is a great book on this topic.
On trading generally I recommend to read Long-term secrets to short-term trading by Larry Williams.
I agree psychology is important, I only touched on it just a bit with one sticking to the plan they make...but psychology would in fact determine the plan for sure.