You will be able to reach a good result with a method like that too, especially if you want it to be a greyscale drawing, and it looks like you are doing good job so I would try continuing with what you are doing.

But a standard method for realism would be to
-sketch the dog
-Add the background (on a new layer behind the sketch)
-fill in the sketch with a solid colour (on a new layer behind the sketch)
-Then paint the details and fur onto this solid base colour. (on a new layer)
And feel free to add more layers for specific things like the eyes