Here is one way to achieve a Van Gogh like brushstroke appearance.
A link to the Photoshop file
A link to the Photoshop file
Notice the use of masks to achieve non-destructive editing.
The top layer of Van Gogh is made black and white with an Adjustment Layer, and the Overlay Blending Mode is used so that only the shading and the texture of the brush strokes appear on the final image.