My 32-years of experience suggests: 1. Don't do anything that you cannot undo. Like, copy the /etc/passwd before running vi on it. Or yelling at a user. Or

My 32-years of experience suggests: 1. Don't do anything that you cannot undo. Like, copy the /etc/passwd before running vi on it. Or yelling at a user. Or upgrading software or operating system -- have backups. 2. Have the trust and authority of your manager. This needs to be negotiated in advance. Warn management of your steep learning curve and warn them to expect outages. Ensure you can tell users to wait because you have a priority list established with your manager. Remind users, if necessary, that they are not your manager. 3. Make a note, even if just by counting, every user request. For 100 users you might expect 50 to 200 requests per month. Be sure management sees this report. It is evidence to support additional hiring. 4. Learn customer service skills. Be able to stay completely calm in the face of the CEO screaming in your face. This requires a lot of "emotional IQ" and probably training and coaching. If you can achieve this level of zen-consciousness just 80% of the time you win. All the other advice posted here also applies. The trick is to adapt the advice to the situation you face, and, when you make a mistake, quickly reverse course. Good luck!