They just do more of it. The Magic usually spend about 35 minutes at the morning shootaround preparing for that night's opponent. Now that they have only one opponent, each player spends more time studying his opponent on tape, then applying that in practice. They learn where players like to shoot the ball, like to catch the ball, like to cut without the ball. Of course, that works both ways.
Teams become so familiar with each other, they can call each other's plays.
After Game 1, if they call a play and a guy goes the wrong way, the opposing player can say, 'Hey, you're running the wrong way. Teams can spring surprises, like a different trap on defense. But the shock value usually lasts only a couple of possessions before the other team figures it out. There are some guys who think they are smarter than other guys in our fraternity. But there really are no tricks.