Number 1, 2 and 3 is not to try to justify your title and impress people with your knowledge. I routinely see new experienced hires immediately trying to show off how much they know and lecture the people who are already there. They usually fail big time because nobody likes them and their suggestions show a lock of understanding.

In the first few weeks listen a lot, ask non-confrontational questions and learn as much as you can. If you are good, you will find areas where you can help and your help is welcome.