Mistake #1: carry out their duties by reacting to problems only as they come up, rather than looking ahead to potential problems and having a solution in place ahead of time.
Mistake #2: Failing to emphasize documentation and training
Mistake #3: Failing to assess strengths and weaknesses
Mistake #4: Too much, too quickly
Mistake #5: Security as a secondary priority
via eviloctal
7. Forgetting Courtesy
via oreillynet
#1: Installing applications from various types
#2: Neglecting updates
#3: Poor root password choice
#4: Avoiding the command line
#5: Not keeping a working kernel installed
#6: Not backing up critical configuration files
#7: Booting a server to X
#8: Not understanding permissions
#9: Logging in as root user
#10: Ignoring log files
via techrepublic