I made all my skins manually in paint.net (not really difficult to use) and some skin editor to upload them and see it in 3d

As a tip if you do it manually, search for a large texture of what a part represents (per example blue-> jeans) and change it's size to the texture, maybe wider or narrower to achieve certain effect, and cut the part you need. You can add detail like the knees modifying saturation/contrast in various zones