Hi there Jacqueline,
A good line training captain must fulfill a couple of roles to be considered "good." First, and above all else, is a relaxed attitude towards teaching, and an ability to let the student make their mistakes (without jeapordizing flight safety). Many trainers I've seen try and use the "gotcha" method, while I've found most guys and gals learn quicker by making an error - a little egg on the face does wonders! I don't intentionally embarrass them, and will often try and avoid it, but sometimes its exactly what is needed.
Second, an up-to-date and in depth knowledge of the aircraft systems, not just to teach, but also to fix any muck up's the trainee makes.
Third is an in depth knowledge of the company ops manual and SOP's, and fourth is an ability to adapt to the changing needs of the student. Sometimes the student needs to make their errors, sometimes they need to be shown, and sometimes they need to have control taken from them.
As for a good debrief, I like the CAL method from the LOS Debrief guide by NASA. Link is here
http://humansystems.arc.nasa.gov/fli...raining_TM.pdf
This method is like the old sandwich method, but focuses on:
1). CRM - How did CRM play a part in our day, good or bad?
2). Analysis - What led us/you to make the decisions we did today?
3). Line ops - how could these decisions impact future operations and have other crews made similar decisions with a different outcome.
That's a very general look at the method, but I've found from a training perspective, that it works very well. In many cases a student who identifies that another crew damaged an airplane or worse teaches a lesson just as quick as anything else.
Last, but not least,the good old positive and negative feedback styles certainly have their place. Good decision making should be identified often during the first flight, and then identification reduced over time in order to show that it is at least the minimum standard. Poor decision making should be pounced on immediately, and anything else....well, that comes with experience as to whether to talk about it right then and there or whether it can wait.
As for the literature...there is a lot out there. Try searching university libraries first, specifically journals, studies, reports, etc.
Edit: spelling