I have mine in a sleeve whenever i'm not using it
This means that it wont get as much dust, as it would if just had it on my desk for hours etc when not being used (at night for example)
But as for cleaning the inside of it from dust?
I have no idea.. it's not a problem now

and I've never owned a laptop where it was a problem
i clean my keyboard often with just a pretty dry (not 100%) cloth thing, and on the screen, i use a microfiber cloth with some cleaning spray i got for some sunglasses i bought. That works nicely

(spray on cloth, then rub cloth on screen gently)