I love to paint the deep woods. There is mystery in the dark depth of the shadows. And the way the light filters through the trees is absolutely majestic! ( at least to me ) What appeals to me above all, is the strong light and dark contrast, which is the entire basis of a good painting.
So many times, I see beginning painters who possess good intentions, but also ignorance of the importance of a strong light/dark balance in their work. It's been said that, "without the dark, there is no light". That is absolutely true!! The darks are what make the lights "pop" and without enough contrast, the end result will be bland.
This principle does not pertain only to wooded landscapes, but EVERY artistic theme and subject. Still life, florals, portraits, whatever the subject,.......all will benefit from a good balance of contrasts.
When thinking about the lights and darks in your next painting, also consider the color "temperatures". Although it's certainly not always the case, a good rule of thumb to keep in mind is to use cooler colors in the shadows, warmer tones in the highlight areas. This will add a huge "kick" to your painting and yield a more refined, professional result.