Find an internal mentor at Google who has been there at least 3 years and came in at the same level as you (or maybe one level above). They will give you a wealth of tips and tricks to navigate it. It's usually easy to find an altruistic soul who is willing to make sure others don't repeat their own mistakes.

Make sure they are not part of your org chain, and that there is a clear understanding of trust so you can talk openly about everything without any fear of retribution. It should be a safe place and a good mentor always respects that.