Well, I've found that ambient room temperature has a HUGE impact on your idle (and probably your load) CPU/GPU temperatures (duh). So, if you have any way to get your laptop running in a cooler environment (e.g. working next to an open window at night, or working in an air conditioned room, etc.), then that would help a lot.
Ok, I just saw that that didn't really fit your criteria, but I hope you might still find it useful. Or interesting, at least, lol.