I always test new solutions on new layers. This way I can easily turn them off, in order to evaluate if these additions improve the image or not. Sometimes, it's also a good idea to let the image rest for an hour or have a good night's sleep so you can look at it again with fresh eyes. If I approve of these new changes then I merge the layer down, otherwise I will delete it. You should try to explore new solutions and have fun with the process. The digital medium is the ideal tool for this as it is very forgiving. Don't get too attached to the painting or you will get stuck with mediocre solutions. Always try to improve. For example, I tested some rays of light coming from the back through the spaceship. I liked this at first but later on I understood that it drew too much attention and conflicted with the focal blue light (Fig.07).
Resize and Check
I resized the image to 5000px. On a new layer I drew some lines with the line tool to check for symmetry and perspective. I tend not to worry about perspective too early on as it may hamper the initial quick painting process. While it can be frustrating to find out that the perspective is quite off and have to correct it, this is usually quicker and easier than it looks and can be rewarding further on. Other changes to the painting at this point were the shift from magenta to orange and the introduction of a white protective piece of cloth to enclose the main character (Fig.08).
When detailing the mechanic I tried to imagine how the light would hit the character, which shadows it would cast, how indirect light would hit his back... I also tried to evaluate the level of reflection of the skin and cloth surfaces. A mechanical arm was added on top to add further depth. Finally, I changed the white cloth to a transparent plastic. Instead of white light coming from a hidden place, now there was the light in the background that was passing through the plastic resulting in a better integration of the elements (Fig.09).