G'day Marshall,

++ They're all good techniques which I use too. I also sometimes add a temporary exit statement: often in a loop to see print debug statements for just one iteration.

I almost always add something like

# TODO - debugging
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just before those things so that they're easy to subsequently find and remove. My normal syntax highlighting displays the commented "TODO" in a horribly contrasting magenta on blue so it's really hard to miss; even without that, it's easy to just search the text for.

"... a really bizarre looking error that I traced back to a ":" instead of a ";" at the end ..."

Unfortunately, that's one mistake I make far too often. It was very difficult to track down when I first used to make it. I now recognise it as just something I do when not releasing the Shift key quickly enough:

$result = function(...):
$hashref = { ... }:
$string = "...":
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It's easy to miss when just reviewing the code because ":" and ";" look very similar; at least now it's easy to find and fix when I get a syntax error reported.