Best I can tell you is that I use a brush, put it in paint and brush the model. :-)
I kind of don't want to share my silly methods.
But really it is kind of like blending, don't try to force a solid color in one go.
On the blue planet I basicly just brushed in two direction from left to right. Because I wanted to look of rings I used mainly a wide flat brush and the thin edge for diffent thickness effects. Let dry a bit and then repeat. After multiple coats with this method it was done. Also the blue planet is done with just a primer gray and one color. No washes or changing colors. Manipulation of opacity is the goal.
For the red planet it maybe harder to explain.
Primer. (Vallejo gray) goes on smooth and will hold.
Red (pick color you want).
Black (to darken color).
I used a wide flat brush with red brushed in random directions. Using the basic concept of opacity at this point it looks like a jacked up patch work of red. I repeated this a few more times. Then taking a crappy brush for drybrushing I stipple (jab) at the planet, at the same time I am brushing patterns of terrain too with the same brush. The paint is some what wet when doing this. I repeat this process with added black to the red. After going back and forth with different colors shades of my red. I use a smaller brush to paint more patterns to blend and accent random patterns.
If you seen me actually paint though the steps (no real ordered steps) most of the time it would look terrible. One advice is to learn what the paint will do when used with water also helped with the painting of the red planet, were the paint would bead and collect.
So try to follow my painting style. Lol :-P