With clothing I usually just get the basemesh into Zbrush, sculpt it, and get it out. I sometimes retopo it too, and optimize it to include folds and such with the least amount of resolution possible, but that's less necessary for non-game models. You base mesh (as carl said) will be hard to sculpt on. You need an even…
You can use the sculpt tool(available in both maya and max) to smooth out the surface. That way you can get rid of the areas which look unnecessary tight with polygons(like the shoulders and the stomach). For the clothes you could just duplicate your mesh, scale it up and then erase the parts which you won't need(you…