We have to consider L and S as vectors, meaning that L+S is maximal when the two vectors point in the same direction and minimal when the two vectors point in the opposite direction. This means that
J = 2 –> L and S are parallel and pointing in the same direction.
J = 1 –> L and S are perpendicular to each other.
J = 0 –> L and S are parallel and pointing in opposite directions.