I have been busy today painting sky's. I use Setacolor paints and hake brushes are my brushes of choice. This first sky is kind of a fantasy sky and I really love the colors. When you do these it is important to start with the lighter colors and then move to the darks. Also leave some white areas since the paints will run together. Keep the brush moving in a scrubbing like motion and don't use too much paint or you will get blobs.
This next one is the sky reflected in the water. Not sure about it but again when painting you have the freedom to create what you want and although I have never quilt seen a sky like this it is my art.
I love this next one. It reminds me of the tropics.
Lastly just a plain old blue sky. For these I go back in with the white to create the clouds after the blues have dried. Important again to leave some white so you can scrub in some clouds. The streaks in the upper right where made by dragging the handle end of my brush through the wet paint on the fabric.