Living through this right now; I've just ended a ten-year stint at Pinterest and finished Week One at a stealthy little start-up. Find someone who needs your h

Living through this right now; I've just ended a ten-year stint at Pinterest and finished Week One at a stealthy little start-up. Find someone who needs your help with a problem in your domain and help them figure it out. Important: try not to solve the problem yourself. Pair with the other person and help as they solve it using the tools you need to learn in order to succeed at the new place. Repeat with at least two more people, hopefully in different areas of the new company. Learn as much as you can about how those areas rub together, and where the pain points are. Document those pain points, politely. Throughout this process, be personally vulnerable. If you're tired or confused or feeling imposter-ish, tell your buddies and connect on that human level. Take excellent notes on the onboarding/ramping-up process, get your buddies to vet them, and share them with subsequent new hires. If the new thing is a startup you might actually be writing the new-hire guide as you go along, which will earn you endless karma.