Personally, for items like clothing, prints, and inorganics; I prefer to do the original work in Illustrator and then raster the Illustrator files into Photoshop. It's amazing--even at low resolutions, how a rastered image will hold up fine details better than a map built from cut and paste--especially with resized patterns and textures. Its a process I used in creating maps for the first version of Poser, and given the size of the maps (and lack of physical detail of the models) you could use with that version, the results came out a lot crisper for painted on outfits than any other method.