While browsing through some website content I found a TechEd 2005 presentation which contained the following slide:
How To Get Your Network Hacked in 10 Easy Steps
1. Don’t patch anything
2. Run unhardened applications
3. Use one admin account, everywhere
4. Open lots of holes in the firewall
5. Allow unrestricted internal traffic
6. Allow all outbound traffic
7. Don’t harden servers
8. Reuse your passwords
9. Use high-level service accounts, in multiple places
10. Assume everything is OK
Go ahead, make my day!