Semi-Transparent fabric
This tutorial is for Photoshop 5.0, but works in other versions of Photoshop as well.
 
1. Choose the doll. 2. Draw the desired shape of the area you want semi-transparent, in this case the skirt.
   
3. Shade and smudge. See the dress tutorial if you need help with that. 4. As this will be semi-transparent I've dodged a bit here and there to enhance the folds. Increasing the contrast works as well if you prefer that.
   
5. Change the layer opacity to a desired setting. I've chosen 50%. I've kept the outline on 100%, but depending on colours it can look better to turn it slightly transparent as well. 6. There are areas outside of the doll that are semi-transparent which are on a white background. These areas can look a bit messed up after you've saved the doll, especially on a dark background. For a better result I've placed a layer behind the whole doll that covers the areas of the skirt that are outside of the dress. I've chosen a colour that's slightly lighter than the outline colour.
   
7. The semi-transparent areas look alright on both light and dark backgrounds.