If only I'd known while I was still part of the corporate world...
1 Never offer to make coffee
In an open plan office there is a ritual where everyone waits hours for the first person to say: "Who wants a coffee?" That person then finds themselves in the kitchen for the rest of the day working as a junior catering manager. Also remember that nobody ever gets to the top of an organisation by drinking stinky teas. No one wants to have a serious meeting in a room that smells of peppermint/rhubarb/aloe vera.
2 Ignore all emails
Working in the post room is not generally a career choice for most people. Yet with the epidemic of email most people spend half their working lives slaving away in their own personal computer post room...