I was wondering if there was a way to stop gumpaste from cracking. These cracks appear after they have dried. Is there something that I can add to prevent this or is there something I can add later (i.e glaze or lacquer, etc.)? I did noticed that the evidence of cracks lessened when I used shortening to coat my hands rather than the powdered sugar. Any tips?

It helps me, when I pull off a small piece of gp to work with, I knead in a little dab of shortening. It makes the piece more pliable.

I never use powdered sugar, once the dough is ready and not sticky. I do use a superfine duster to cornstarch the work surface for things that need not to stick.