Simplifying
It's easy to get bogged down by details and information. In a complex scene such as this harbor at sunset, the key to success is simplifying. The viewer doesn't need to see every single detail in a scene. Leaving out unwanted details makes a scene more interesting and helps the viewer become part of the scene and actively participate.
For this little painting I simply and carefully observed the large shapes and rendered those, doing my best to not add in extra details. Dots and dashes will suffice for background information, and a few carefully placed marks create boats and shadows. Here is a photo of this painting in its early stage. Find your ability to see big shapes and half the work is done toward creating a beautiful, complex scene.
