I would guess from your assessment that your difficulty is "muddy or inadequately separated shadows. However there are several other conditions and considerations. If you have a thinner negative with greater contrast then the possible problems that may exist fall into certain areas as I see them. The basic conditions all originate with the camera negative since the paper is a fixed known and we must work within it's parameters. The possible failures that originate with the camera negative are either the negative is under or over exposed and it is either under or over developed.
Originally Posted by Francesco
Taken from the standpoint of the appearance on the print these would appear as follows.
1. The print exhibits a tonal scale that exceeds the papers ability. This would be blown out highlights or shadows lacking in any detail. The negative shows adequate shadow detail.
2. Shadows values that are too deep and depressed. With the shadows exhibiting inadequate tonal separation. Negative shows inadequate or no shadow detail.
3. Highlight tonal values that are compressed. With inadequate highlight separation. Negative shows adequate shadow detail and highlight blocking.
4. The print exhibits inadequate contrast. Either the shadows are weak or the highlights are gray. Negative shows detail throughout.
The remedy for these conditions are as I see them:
1. Decrease negative development time in the future. For this negative use water bath or other means of compensating development.
2. Rate the film lower or place the shadows higher in the film exposure. Both effectively accomplish the same thing since we are giving more exposure. This will place the shadow values further up the characteristic curve.
3. Decrease negative development. Decrease film exposure if the shadow densities are high.
4. Increase negative development. Print on higher grade paper.
Apart from that is the issue of developer choice. Michael Smith's Amidol formula works. It has been proven in my experience. Other choices may not and probably will not give the same results.
There may be other conditions and considerations that do not come to mind at this time. However this should give a general course of action.