How to clean PCB?

There is a bunch of gunk on my R/C car's PCB, how do I clean it off without damaging the circuits?

I reccomend using compressed air. If that's not an option go to office depot or CVS and pickup a canister of keyboard cleaner, it is just like compressed air except it contains little molecules of synthetics that whisk away any foreign matter. I hope this helps. -M4

Whoa! Using compressed air is a bad idea, unless it goes through special designed ionizing air guns.  Compressed air will create a static charge and may kill your circuits if you have semiconductors.  Use a soft tooth brush lightly.  Or clean with electrolube SWAS, then dry it properly in the oven for say 24 hours at 70 degrees C.

Sorry, I didn't mean actual compressed air!  I meant the canned cleaner.

It's just easier to refer to it as "air in a can" than compressed ionized gas.