In a previous question I asked if it was possible to model a specific human face. The answer I got was that its used more as a tool for approximating your target face, then manually adjust the mesh to get as close to the desired look as you care.
My question now is how does one do that? or rather, what is the best workflow? I tried both modeling and sculpting the changes, but when I applied the various expressions, the shapekeys ended up being way out of wack. Is there a way to preserve the shapekeys, or apply the same changes to the shapekeys at full value as gets put on the basis?