Following the road for 100m to the first bend reveals several dirt tracks to the right and a broken camino sign. It is of the post-and-tile kind, and the tile has been removed. The desired track is the rightmost one.
You can alternatively take the road, which is marked with the old camino arrows to Gramatinha, and then to Casais Maduros.
The dirt track that you turned right on will take you to the road and to Casal do Soeiro. Several more arrows along the way are missing, but the way is clear when you remember that you should NOT walk on the road. Several pleasant tracks bypass the road all the way into town. On particularly wet or rainy days, there is no harm in sticking to the road so long as you mind the minor traffic.
Pass straight through Venda do Negro, turning left at the fork in the road at the far end of town.