Sketch San Miguel de Allende: Learning to think about landscape painting #1

This is a small (5 x 7) study from San Miguel de Allende, an amazing place to visit.  Donkeys carrying things are a common sight.  Learning to paint landscapes is one of my 2015 goals.  I had read the wonderful resource book: Carlson's Guide to Landscape Painting (link) a couple of years ago, but I wasn't ready to understand it then. This painting is my first  2015 implementation of his breakdown of a value plan of a landscape.
Simply: 1. the sky (which is the source of light: even on a cloudy day) is the lightest value.
2. flat, horizontal ground receives the light and therefore, is the second lightest value
3. vertical element (trees, buildings (people and donkeys)) don't receive light, so they are the darkest elements
4.slopes (mountains, slanted rooftops) are in between the ground value and the vertical (dark) value
Don't break up values

Try a small sketch with a pencil thinking this way: simplify like valued-shapes (i.e. link all the trees in the tree line and define only by the shape of the tree tops). Great way to start, isn't it?

Squint at this painting now and see if you can see the basic values...
So, I am off to work on this further