when I use gumpaste (Wilton's recipe) to make flowers or other accessories, I find once it dries, its very brittle. It doesn't take much to break a piece off. So, should I mix gumpaste and fondant 1/2 and 1/2? Does someone have a recipe for a good gumpaste. I also noticed once it dries (the gumpaste) I find the texture of the petals or leaves do not have a smooth looking finish. Cetainly not smooth like all the flowers I've seen on cc.

This depends partly on the climate where you live, I think. In my hot and sticky part of the world, gumpaste (and sometimes even pastillage) is the only thing that will work for flowers and figures. If it's not so humid where you are, you might be happier with a fondant/gumpaste mix or even fondant with a hefty dose of tylose/CMC, which will make your fondant dry stiffer. My favorite home-made gumpaste recipe is Nicholas Lodge's, although I usually just use Satin Ice ready-made.