According to Lori McNee on Fine Art Tips, "Careful observation of what you actually see, rather than what you think you see ? will help you paint believable water." It's important to use quick, energetic brush strokes when painting ripples over water by employing a side-to-side technique and a small, thin brush. This technique requires dragging paint from light areas into dark areas and vice versa.
McNee says the technique that provides the best results for water ripples relies on the structure of the underlying body of water. Larger bodies of water, like lakes, are generally more still at the surface, so they have small gentle ripples that are barely noticeable. Creeks and small streams, however, flow their water over stones and through cracks, so their ripples are much more noticeable. In both cases, a back and forth technique provides the most realistic ripple effect to painted water.
Start by quickly and energetically dragging paint from the darker part of a reflection into the lighter parts of the reflection. The waviness of the stroke should follow the structure of the ripple. The brush needs to be cleaned before repeating the process by dragging paint from the lighter part of a reflection into the darker portions of the reflection.