See the following links for troubleshooting techniques and tips:
Logical Troubleshooting (a classic app note from HP – now Agilent)
Troubleshooting Theory and Practice from AllAboutCircuits.com
Troubleshooting and Repair of Consumer Electronics Equipment from repairfaq.org
Trouble-Shooting Tech Tips from RSR Electronics
Intro to Logical Troubleshooting (US Army)
Troubleshooting Strategies Video
Debugging Rules! poster
Books:
Debugging, by Dave Agans, from Amazon
Electrical & Instrumentation Tech 