Thank you Tom for the tip...i will try it out for sure!
I do practice for 2 reasons...to get closer to natural looking contours and to learn the material i work with, so i can get as close as possible to the tooth i want to copy by having as much as possible control of what i am layering.
Now, what looks natural or not i think it is a bit subjective, i have done cases that they looked great on the model(in my eyes at least) and in the mouth they just looked ok, the characterization was almost lost next to the rest of the dentition...
In my opinion to get close to natural looking teeth...1. contour and surface texture and 2. contrast and depth that can be acheived with X amount of different powders.
For me, an opaque dentin-dentin-enamel layering isnt enough to do natural looking teeth.