Searched for the word combo "clean AND laptop" and "clean AND fan" and "sink AND clean", but no real dedicated old thread surfaced, so here it is. Throw your cleaning tips in.

First one:

Was following a brief exchange of someone removing a thin film of dust from the fan-blades over the CPU and the device dropping 20C or more. It was thought that possibly the cleaning action may also have addressed a thin dust layer on the heat-sink, but here is just a simple observation...

Me quad desktop has a sidewall with four 12 cm outward directed low rev fans, none temp controlled. While holding hands at about a 4 inch distance there was barely a feel of air push. Unplugged the fan set and saw that very same dust film on the blades as seen in the previous para. Took a paintbrush and thoroughly removed all residue. Plugged the powersocket back in, replaced the sidewall and low and behold, at 1.5 foot could feel the push again... and just a tinge more silent. No temp difference as Speedfan just was compensating the main 8cm fan in the tube that leads to the CPU.

Ergo: Fans themselves even when only slightly dusty loose performance, probably having reduced revs on the go. Not once a year, once every few months and in my case, did not even have to power down [it's advisable though]

edit: some orrible word repetitions in 1 line.