Underpainting?
The more regularly one paints, the better one gets. It's as simple as that. Is it muscle memory, or developing technique, or discovering all that is possible with the materials, the implements at hand...? Probably a combination of all these things.
In the past month, I have worked on three landscape paintings. I began two on canvases toned with a bright orangey-red acrylic paint. I drew my scenes fairly simply using pencil or acrylic paint. Then started working with oil paints in layers.
The third one I began with an underpainting using burnt umber and titanium white acrylic paints. I thought working tones out would make the eventual work of painting the scene simpler.
What I have discovered is that there is no need for this. An underpainting to work out tonal contrast does nothing to improve my work, not right now at least. Not ruling this out altogether as a technique, but in my other two works, working in thin layers, in the actual colours I intend to use, gives me more of an understanding of how I want to proceed, and a chance to develop tones within the colours I have chosen. Far more productive.
Not ruling anything out though. Disclaimer ;D