I use rubbing (isopropyl) alcohol and Q-tips.

[Edited for more tip]

Oh, and one other tip is to get a very soft tooth brush, preferably one of those one with the uneven bristles.

Those kind of ones that you get for free on the airplanes are perfect, so if you see something like that in a dollar store, that'd be the one. I wouldn't be using an Oral-B brush as you might brush off something from a circuit board.

Then for those areas that are suborn, you can soak a Q-tip and then press the Q-tip on the area to clean to help the alcohol soak in. Then you can use the tooth brush to gently brush away the debris and not get cotton stuck to anything.