How to paint wings, smoke, portraits, drama and more!
The first thing that you should bear in mind when tackling this subject is that even the translucent matter that makes up these wings is still going to be affected by the lighting in the scene to some degree. A translucent or transparent object can experience specular highlights, and the placement of those highlights vary depending on the position of the viewer.
For example, if you’re walking outside on a sunny day and you notice someone wearing sunglasses, you’ll see specular reflections on the lens. If you’re the one who’s wearing the sunglasses then you won’t notice any reflection on the lens of your glasses, because the reflections are on the outside.
The same principle works here. If you paint the side of a wing facing the main light source, you should paint some specular highlights, even if this means losing some transparency. When painting the side of the wing that’s away from the light, you can ignore the highlights and focus on creating the transparency effect.