Opacity Hell
The best way to introduce you to the subtlties of new-subtractive-transparency
would be for Phil Miller to upload the huge thread about it (that he's got
archived) from late last year.
Phil?
Re bump maps… Martin's response is pretty right on, in addition to stressing
that the bump map ought to use gradient bumps instead of harsh luma stepping.
Using a proper bump map with some map filtering will provide the highest
quality bump mapping you can achieve with any commercial 3D renderer this side
of Renderman.
– G