One thing I've learned to do is to dust off my toys regularly. Something I never thought of doing when I was still a kid. Of course you can avoid having to dust off your toys by keeping them in the box. I'd prefer to brush them weekly but sometimes they can go a month without any dusting.
For dusting my toys and the innards of my computer, I use a regular painting brush with the softest and finest bristles. Soft bristles prevent it from damaging the figure, most especially the paint job. The fine bristles ensures that the brush can reach every nook and cranny of the figure.
I bought the paint brush from the local hardware for around $1. I prefer to dust it away from the display cabinet, this is to that the dust won't just end up back in the cabinet with the toy.