I really wish Blender had a way to snap to another surface when using some of the sculpt brushes. Using Grab and smooth brushes while snapping to an underlying surface would be very convenient during retopology. I know other software has this feature, and I think there are some addons that can help, but is there a way to do it with built in tools?
If possible, you could drag topology across the surface with the grab brush and relax with smooth. Pinch is also quite useful.
Sculping kind of works for adjusting the mesh with Shrinkwrap on top, but you have to apply the modifier quite often because the mesh will move away from the surface.