Let's take some time to study this terrific Rex Brandt painting;
Look at the sky first. See the overall light grey wash? If you had seen that color and value as the "common denominator" for the sky, mixed up a generous puddle of it, and selected the biggest brush that would comfortably do the job, you'd be all ready to lay down the wash, right? Before you do, though, remember to ask if there's anything you want to reserve. In this case, there's that white building to paint around. You also need to consider how long you want the sky area to stay wet. How much soft-edged work needs to be done before the wash dries? It looks like there are two colors to apply; the darker grey and the burnt sienna. Can you do the sky wash, the grey clouds and the burnt sienna without washing your brush?
If you're inclined, make a copy of Rex's "Mud Puddle", but I'd like everyone to also interpret this photo;
At first glance, this scene appears to be all soft edges above and all hard edges below, but let's zoom in on the rocks;
See where the first layer colors change from warm brown to cool grey to green? The profile of the rock against the sky is definitely hard, but the mid-value transitions within the shape could be soft. How about the strong dark shapes and lines? What kind of edges do you want?
Would you paint the sky first or the rocks? Why?
How many layers does the rock comprise?