Scenario 1: Use lower film speed (with the same film) -> slower shutter speeds or wider apertures.
- Expose more = more shadow detail.
- Develop less = don't block up the highlights because of the increased exposure.
Scenario 2: Use the same film speed -> change developer.
- Use a speed enhancing developer. Xtol, TMax, Ilfotec DD-X, Ilford Microphen, for example.
Scenario 3: Change developing technique
- Dilute your developer more for longer developing times.
You can combine any or all of these techniques, depending on how much shadow detail you want/need.