The tutorial is pretty detailed now. After going through it, it was clear how to play.
A bit annoying was that the 9 th level was the first "real" level. So there are 8 level for the tutorial and just 4 real levels. That doesn't seem well balanced.
I don't know how to describe my strategy. I also look at the first steps/opponents for each hero and then i just go looking what is next and which hero can gain which item that is needed for any further steps. Also I usually asumed that the most complicated, longest way is the one to choose.