Because watercolor is a transparent medium it makes sense to work from light to dark . A dark can cover a light more reliably than a light can cover a dark. It's your lucky day when a scene or image resolves into a sequence of light tones first, followed by middle values and then darks.
In this scene the shapes progress nicely from the lightest (sun) to the darkest (distant mountain). That means you can simply apply the lightest tones first and put progressively darker values right on top of the lighter ones. For example, the middle value of the grass could extend back all the way back and up the mountain. The mountain can then be applied as a layer of darker paint.
In this Lake Union scene what came first? The lightest area appears to be the pale yellow in the sky. The shadows on the boats are also very light. Both could be applied at the same time, followed by the clouds. Then the middle value ochre on the boats and the water. The line of trees and the ports on the boats are darkest. They can be placed anywhere you want them since they are dark enough to cover any of the earlier layers.