A good start is half the success. and how do you ensure this at you new job? It's a serious challenge for product managers who are moving into a new job. The challenge becomes more stiff if you are moving into a newer domain, and are going to work with whole new set of professionals you never worked with.
From my experience I have coined down first few steps that a product manger should take as soon as he gets onto a new job. My fair assumption is that you would have learned and read enough about the domain in which you are going to operate, however knowing things from outside may not be as clear and absolute as you get to see when you get into the system.
Learning Steps