In this video in the QuickStart series I show how to take a mesh your sculpted and eihter extract a normal / displacement map for it, or recreate it perflectly using your retopologised mesh. in this way you can sculpt away form very low res bases and then bake these details into your retopped mesh to make for a better target for normal mapping or as a target for displacement maps in your target application. you can of course also continue to sculpt and get even higher polygon counts with a better flow.