The snake has different colors than our scene. Let’s correct that by adding a clipped Curves Adjustment Layer and using the settings shown below.
Create a new layer and change the blending mode to Overlay. Clip this layer to the snake layer (alt-click between the two layers) and with a round soft brush at 10% paint some basic shading on the snake (highlights on the top of the snake and shadows on the sides).
Create a new layer below the snake and paint some shadow.
Now let’s add some overall lighting to our scene. Create a new layer and change the blending mode to Overlay. With the round soft brush at 10% opacity paint with white and black in the areas indicated below.
Create another new layer and change the blending mode to Overlay. Paint with white on the areas indicated below to add some specular highlights to our characters.
It’s time for the final effects. Create a new layer from all the visible layers (Ctrl + Shift + Alt +E) and convert it into a smart object. Add an Unsharp mask effect (Filter > Sharpen > Unsharp Mask) to the smart object with the settings shown below to sharpen our scene.
Add another Unsharp mask effect (Filter > Sharpen > Unsharp Mask ) with the settings shown below not to sharpen the image but to increase the contrast.
Finally add a Gaussian Blur effect to the smart object (Filter > Blur >Gaussian Blur) and change the blending mode of this filter to blending mode (click on the little arrows sign indicated below to open the blending options).