I focus mainly on the art of troubleshooting. " Why troubleshooting?"  you may ask.
  • Troubleshooting is the highest form of networking skill.
  • Inside-out knowledge of the technology is a prerequisite.
  • You must be able to "crawl under the skin" of IOS™, and fully comprehend it's  strengths and weaknesses.

How do I focus on troubleshooting? I'm running  a technical troubleshooting blog and I also coauthored an advance troubleshooting workbook which presents you with such problems that will make you scream in horror, or just challenge your networking skills.