Tips

Use highest quality whenever possible
     RAW on the camera
     Non-lossy compressions during workflow
     convert to jpeg *last*

Get the correct ICC Profile for your camera
     Your camera's mode also matters.  Neutral or Faithful are 
       good choices

Be Patient
     Proper processing will take a while
     10-15 minutes per photograph is not unheard of...

Of course, it depends on your source image...
     won't make a picture better, but this will prevent you from 
        ruining a good shot