It seems so obvious now that I’ve solved it but ever since I started drawing I’ve been wondering how to get rid of the white. Doesn’t matter how many details you draw there will always be a part of the picture without details and that part will be white.
The painting I’m copying has no white in it. But what do I draw after I’ve drawn the sun, the clouds and the water?
This afternoon it finally hit me.
I should start out with a background color. Either the lightest color there is in the picture or a part of the picture. In this drawing I’m doing that with the sea (lower part of the drawing, isn’t jet there). Or I use a color that I can mix to get the colors I need.
In the upper part of the drawing I use the lightest pink I have in my drawing box. That color isn’t actually in the picture but I can mix it to get the dark purple parts of the sky and the dark gray/blue clouds.

Using a background color has one other purpose. Pencil colors are usually far more interesting when you get them by mixing a few colors then by just using the colors in the box.