This looks like good advice to keep in mind on your next plein air outing.
I've paraphrased this information from a recent article by Alfonso L Tejada, a plein air instructor.
3 steps to gain awareness and creativity when painting plein air:
Visually study the location and conditions prior to painting and identify central subject of work. This requires developing a visual sensetivity to recognising sun patterns and light sources, and then doing a 5 minute thumbnail sketch recording contrasts of light. The three steps to develop this preliminary anatysis are topography, structure, and contrast.
Topography: identify a ground plane as a reference for all the other elements to connect with
Structure: identify the vertical and horizontal elements of the composition
Contrast: most important step. marking the dominant areas with shadow and light then identifying the basic range of primary colours of the location to determine the palette colours you will use.
Following these 3 steps will help establish the structure of your work by reinforcing your composition, the focal point, the light values, and a brighter palette.