I think style comes out of script analysis.  Five different people can read the play _Hamlet_, and each could come back with five different messages Shakespeare was supposedly trying to communicate.  I've heard everything from take it at face value--it's the story of a really mixed up family, to the fact that it was during the time Queen Elizabeth and Mary Queen of Scots were battling and it was somehow a political comment of the time period.  I've also seen productions where the apparent psychosis of Hamlet is stressed and not the underlying reasons for it.  But to find the real reason, you have to analyze the play.  It's really about King Claudius killing Hamlet's father (and Claudius' brother) for the throne.  The Ghost of Hamlet's father gets Hamlet to avenge him, and everything from I, 4 in the play that Hamlet does or says is to find away to dethrone and/or kill Claudius and Gertrude.

There is a lovely small book on play analysis called _Backwards and Forwards_ by David Ball.  It's awesome.  Much better at teaching someone script analysis than the _Poetics_ by Aristotle ever were.

Now, after you analyze the play, most directors pick a theme to stress.  I've seen _Much Ado About Nothing_ where theme of people behind masks were used.  I've also seen the same play with the theme that love comes to those who don't look for it. 

But theme is secondary to analysis.  When everything else starts to fall apart, you should always be able to go back to your foundation--the script.  Don't just make directorial decisions based on theme if it's not really in the script.

JCCTony:

I'm gonna shock the regulars here and tell a story

Couple of years ago, a university theatre nearby was doing The Tempest.  I wanted to audition for Caliban; oh boy, did I want to audition for Caliban.  I got books out of the library about Caliban (yep, there are books about the character!), I studied annotations and commentaries, I put together a monologue based largely on "Caliban upon Setebos."

Then (for reasons not relevant here) I couldn't audition.

Anyway, we went to see the show.  Now, for six months or more I'd been talking to my wife about what a great, profound, deep role this was, one that has caused arguments between commentators for four hundred years.

Her response afterwards?  "You wanted to audition for THAT?  Why?"

And she was absolutely right.  The role in this production was slapstick, comic relief.  It wasn't the actor's fault; he was good.

What was the difference?  The director's interpretation.  This director obviously saw Caliban on a par with Quince in Midsummer.   Exactly the same lines, but a completely different interp.  What he did, how he spoke, how he moved -- all very different from my imaginings.  (Note also that I'm not saying I was right about the interp; if I had played the role my way in that production, it would have KILLED the show; it would have been WRONG for that production.)

Another famous example:  Cat On A Hot Tin Roof.  Is Brick gay or not?  Is Maggie really pregnant at the end or not?  Very important questions that the text won't answer for you.  (You may get closer to an answer, depending on which version of the text you use, but never mind that for now.)  Who decides?  You.  The director.

Same text; completely different plays.

That's how you make it your own.