Fill your jars with warm water. These will be used for thinning paint and cleaning brushes. The jar for your brushes should be large enough to hold your brushes without them falling out or tipping the jar
Squeeze your under painting colors on to your palette.
Colors
Pthalo blue
Payne’s gray
Dioxide purple
Raw umber
Mars black
titanium white
Use white to alter the shade of the darker colors here.
Proceed with the Darker Colors
Use large, flat brushes.
Mix a little water with your paint. This will allow you to create thin washes of color.
Start with the darkest areas using the darker colors.
Avoid hard, crisp edges.
Allow your first layer of paint to dry fully.
You will be building your colors up using thin glazes of paint working from dark to light.
Work wet colors into wet colors. If it gets to dirty, dry it with a hair dryer
Squeeze your lighter colors on to your palette. Lighter colors may include titanium white, cadmium yellow, cerulean blue, cadmium orange and possibly violet.
Proceed with the Lighter Colors
Keep the layers very thin. You need to see the previous layers shining through the current layer.
Allow the edges of your paint to blend a bit, skies don’t have hard edges.
Continue to build your colors using thin layers.
Build your colors from dark to light.
Tips
Mid-day, you’ll notice that at the zenith overhead the sky is a deep blue violet color.
As the sky transitions to the horizon it becomes lighter and warmer with less color.
When the sun is low in the sky, the sky near the horizon can be very warm with yellows, oranges and reds.
Clouds reflect pretty much all light frequencies equally. That’s why the sunlit side of clouds appear whitish. The larger and more dense the cloud, the darker the shadow underneath. That’s because most of the light can’t get through to the bottom.
Clouds also have a dark, light and mid tone.
The sunlit side of the clouds overhead (nearer you) are more intense and whiter than the sunlit side of clouds at the horizon.
The sunlit side of clouds at the horizon are less intense and warmer (pinkish). That’s because of the scattering effect in the atmosphere described above.
Clouds don’t have defined hard edges, they simply grade softly at the edges and transition boundaries.
Shadows in clouds are generally grey but the underneath sides of clouds directly overhead can reflect a lot of bounced colors back from the earth.
For example: See above.
Shadows of clouds overhead can be quite warm due to these reflections.
Often, the shadows in a cloud are EXACTLY the same value and the sky behind it.