There's already sort of some information on this within our community-faqs:
How do I troubleshoot when I have no clue where to start?
How do I troubleshoot hardware issues related to a computer freeze/crash?
How to Diagnose a Pre-Operating System Load or Hardware Issue
Feel free to either update this with more detailed information, or if the stuff you're thinking of writing would be better suited to a new post, make sure to reference those.
