I mostly use SciTE for editing and use its default colours. A lot of thought seems to have been put into them, and they work pretty well. Comments are green; keywords are blue and bold; certain operators and other punctuation are black and bold. Scalar identifiers have a pink/red background; array identifiers have yellow backgrounds (and so does qw(...)); hash identifiers have purple backgrounds; regexps have green backgrounds. String constants are kind of purple; numeric constants are kind of aqua. That's about it, I think.