I recently found out (just take a look at ToxicAngel's postwork), that these kind of things require a rather old fashioned asset that is not in the menus of Photoshop. Just plain painting skills. Knowledge of how to paint something like glass. I once looked over the shoulder of someone's father, who made still lives. He painted a photorealistic glass with some five strokes of white and black over a completed background. Fluids tend to be little more than refraction and reflection. And indeed, that is very hard to accomplish. The teardrop tutorial is a good example by the way. It is just shadows and hightlights, as I recall. And those skills (Which I do not claim at all, incidentally).