congratulations you are our new network admin

how do or how would you take over a a new system. in a situation where the sys admin has gone for study leave of two years and you have to handle it from then on or just plain new job with subnets in country x y z p and iraq, ther situations we often find ourselves in are endless.
i would like to take this opportunity to ask those who have been there… to tell us how they managed and share their experiences if they do not mind and maybe give some of us who are heading in those directions afew tips here and there. all experiences will be appreciated