Thinking about Light
One of the fundamentals of drawing and painting is to consider the effect of light; both in how to use it and how it affects the appearance of your subject.
Classical masters of natural light include Rembrandt and Turner
Strong lighting creates contrast and depth
Light reflection in this work by Turner adds drama
In the case of Landscape, think about the time of day you are working with. Strong sunlight creates strong contrasts and deep shadows, whereas light at the end of the day is softer so, forms are softer too and tones are muted.
This image by Vittorio Giardino captures the mottled effect of sunlight through trees.
Now, note the soft light and long shadows in this picture by Peter Sheeler, denoting an evening scene