I’d be happy to tell!

First I’ll choose a picture to shade.

Then I go to my swatches and select a color, my shading colors are circled in yellow. Choose any color that you want or one that best matches the picture.

Create a new layer. Then set the mode to multiply

Draw on the area that you want shade to be in.

Now, I think the shading is too dark, so I’ll bring the opacity down.

Much better, but the shading isn’t as lively or colorful as I wanted it to be.

That’s an easy fix, however. Go to Image<Adjustments<Hue/Saturation. Since the shading is on it’s own layer, you don’t need to select it or anything like that.

Now just mess around and see what works! All I did was just change the hue and increased the saturation.

AND, as an extra, I’ll show you lighting, since I do that with Sweet Scent’s fur.

Similar to before, create a new layer, except this time, set it to linear dodge.

Draw on the areas you want light to hit. Maybe bring down the opacity if you want, and you’re done!

I hope that was helpful! Now, I am a Photoshop user, but I’m sure this technique might work on Paint Tool SAI, but I haven’t used it before.. And I know it should work on GIMP as well.

Happy painting!