Here is a list of 10 things they don't teach you in design school. Many of these are applicable for just about anyone coming out of school (even some who have been done school for quite some time).

Some of the points that I feel are most important include (and in my own words):

#1 - Your portfolio is more important than your diploma.

#3 - Your clients really only care about you getting the work done and more.

#5 - Always, always backup your data.  Have an onsite backup and an offsite redundant backup.

#7 - I always get my clients to at least sign a Non Disclosure Agreement (NDA).