in reply to RFC: Basic debugging checklist
If you use good IDE then 2, 4 and 5 become either redundant or trivial without making any code changes.
Running your code through PerlTidy can show up issues hidden by slack indentation or incorrectly paired tokens (quotes, brackets, ...).
It often helps to comment out chunks of code or put temporary early exits into subs so you can focus on the problem area. That technique can be counter productive if you forget to restore the code though!
Use a revision control system so that you can back out of large changes easily that may have been made while tracking a problem down.
True laziness is hard work
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