Color Blending

 Yellow, Red, Blue blend

Blue, Black, Red blend

Using the brush on very low flow (1-5%) and a little bit of a lowered opacity (60-80%) I was able to blend the colors efficiently. I overlapped the colors and selected the resulting color in the middle to blend and continued with that process.
PS. It looks a lot better than this. The files must have lost some quality when converted to jpeg.

Brushes

Some more experimenting with brushes! I made the stars by modifying the brush to have a high scatter so that I could paint several at once rather than painting each individual one. I also decided to create a planet because I wanted to practice making spheres. I like the look of it and made it smudged to give it a natural look. It reminds me of Mars. I also put in some ambient white light in the background by using a large brush with low opacity to lighten it up a bit.

Brushes

Here is another experiment with brushes. I upped the size of different brushes to the point where they were square-ish with 90 degree angles. By lowering the opacity I was able to get different shades by simply layering them on top of each other. This created a cool camouflage effect so I went with it. I also made it smudged at the end by using another brush at a large size.

Brushes

Here I was experimenting with the different brushes and settings. First I set down a general idea of what I wanted, then painted on some grass with the grass paintbrush. After that was the fun part: the clouds. I knew that I had to make them wispy and see through like natural clouds so I turned down the hardness and erased a lot.