I just use a stiff makeup brush, while blowing... seems to get most of the dust out. Occasionally, I will remove the keycaps and brush it out properly. By far the best way to clean it, is to keep it clean though. Use a dust cover when not in use. Anything will do... even an old t shirt. Another advantage of that is keeping UV off it when not in use, especially with older, vintage boards, as it slows down ageing and yellowing.