In front of a mountain stream, the hardest decision is rarely which colour to mix. It is what to leave out. A river offers far more than any panel can hold: rocks, spray, moss, light flickering through the trees. A painting begins the moment its edges are chosen.
The edges of a picture are more than a frame. They are the first act of composition. Shifting the framing by a few centimetres can change a painting completely. A rock that felt heavy in a corner becomes the anchor of the whole scene, and a bright patch of foam near the edge pulls the eye straight out of the picture. Time spent here, often on several small thumbnails, is never wasted. What is included matters, but what is excluded matters just as much. Leaving things out is where a painting gains clarity, and often its poetry.
The next question is what made the scene worth painting. Usually it is one thing: the curl of water over a stone, a glow of turquoise in a pool, light catching on wet rock. That becomes the centre of attention, and everything else in the painting should serve it. This one area deserves the greatest precision, the crispest edges and the most careful observation, while the rest settles back, softer and quieter.
Contrast is what makes this work. The eye goes first to where the strongest differences meet: light against dark, warm against cool, sharp against soft, saturated against grey. When contrasts are scattered evenly across a painting, the eye wanders and nothing feels important. When the strongest contrast is saved for the centre of attention and everything else is calmed down, the painting breathes.
Finally, there is the path the eye will travel. Rivers are ideal for this, because the water itself is a path. A diagonal of moss, a line of stones or the direction of the current can lead the viewer in, carry them to the centre of attention, and then let them wander gently around the picture rather than out of it. Lines running straight into a corner deserve special caution. They act like an exit door.
None of this is a rule to apply mechanically. It is a way of looking. Faced with any scene, it helps to frame it with the hands, ask what is truly compelling in it, and notice where the eye lands first. That is where the painting begins.