Don't talk, just listen for the first few days in your new job

Yes, curb the tendency to talk about how great you are and the big shot you were in your previous job. Stick to talking about your previous responsibilities in a brief fashion and you could add the learnings you had.

This will help you in: 1) people will not be prejudiced about your interest in this new job 2) expectations will be moderate and not very high 3) you will not come out looking like someone who brags 4) will help people open up and talk more about themselves as they wont feel any lesser then what you are.

The key is to listen, probe and figure out the dynamics. But this does not mean you clam up, just ensure that you have a brief description ready when people ask you where you are from and what you were handling in your previous job / company. Focus for the first few days / weeks would be to understand people and "how things get done here" and therefore listen more and talk less!