When you play 19 seasons in the NBA for a list of coaches whose number rivals the population of Buffalo, you pick up a few pointers along the way. Jason Kidd learned a lot on his journey. He learned accountability from Rick Carlisle. He learned offensive ingenuity from Danny Ainge. He learned preparation from Lawrence Frank. Yes, he learned how to do a lot of things. And he also learned how not to do a lot of the same stuff. “The biggest thing is you have to be prepared. Players can sense when someone’s not prepared. And you have to communicate. Those are some of the things offhand,” Kidd said yesterday when he was officially presented as the Nets’ choice to succeed P.J. Carlesimo as the 18th coach in the franchise’s NBA history, a first time coach who is inheriting not a rebuilding mess but a playoff unit. Kidd seemed to be counting the days until he can implement what he has learned to do — and avoid — as a coach in nearly two decades of sure bet Hall of Fame brilliance. “Some of the things not to do? Time is critical. When they see you’re not starting things on time or you’re not prepared, then things can go south quickly,” Kidd said. The big rap on Kidd is inexperience. Eleven days ago, he was announcing his retirement. The thought of coaching was always in the back of his mind. And the thought exploded to full blown desire when agent Jeff Schwartz reminded Kidd he could not spend the rest of his player retirement on a golf course.