Back to Maass--Raising the Stakes

In last week's Maass class we were reversing motives; finding different ways to motivate the characters into what they do in the story.  Now we're working on raising the stakes. But as Maass says on page 60 of the book, the reason we care about the character when the stakes get high is that we care about the character, period.
 
And therein lies the rub, eh?

We've all read books where we really connected with the characters, and books where they seemed, well, flat.  Maass has already covered a few techniques that he says will help you connect with your reader through words: open with the character in action, show him/her with heroic qualities, have them demonstrate larger-than-life qualities, etc. 

But on page 61 he says that by clothing your protagonist(s) in a cloak of "high principles and codes of personal conduct" you'll create a character who has value, who is worth saving in the readers' eyes.  A book must have, he says, "high public stakes and deep personal stakes" to have breakout potential.

This, of course, is work that's done well before Word One gets set down.  You have to know and understand your character at a very deep level to know what he or she stands for, what matters to him or her. 

So how do you do that?  I've taken a wonderful class with Alicia Rasley that forced me to go deeper, and it was a great help.  I've used Meyers-Briggs personality tests.  I've interviewed my characters.  I've read about their occupations, their time periods, and a zillion other things.  What do you do to dig deeper, to really understand the heart and soul of your characters so you know what matters to them, and thus what you can put at risk?