Tinnu's quick and rough digital painting process

I thought some digital painting newcomers might be interested in my process, so I took some screenshots while I was working on my latest piece "The Challenger". Unfortunately, one of the screenshots was corrupted and I forgot about taking them later in the process ^^" *coughs* As you see, I'm still learning myself and far from being a pro but I just wanted to share some quick advice with the (non-professional) community.

The sketch doesn't have to be clean or accurate, it's just a guide. I usually reduce the opacity of the sketch layer once it's done to around 50% and start blocking in colour on a new transparent layer below.

After you have settled on a colour scheme, avoid adding new colours, but use the colour picker to pick colours from all over your painting, so the colour scheme looks unified and harmonious. Keep in mind the three principles of design...

REPETITION (use the same colours, shapes, etc. all over your image but keep it balanced and not too busy)
VARIETY (use different hues of the same colour, use the same object/shape in different sizes, with different textures)
UNITY (try to keep it harmonious and balanced)

Brushes
Most of my brushes are taken from the brush kits of some really famous artists and can be found at digitalbrushes.tumblr.com/ ... also check out this wonderful chalk brush by Feohria feohria.deviantart.com/art/Cha…

Working size: Never smaller than 1,000 pixels, but in 99% of all cases I go bigger than 2,000 pixels (height and width). 
Software: GIMP 2.8 (free open-source Graphic Image Manipulation Program) www.gimp.org/downloads/

Some individual processes used in GIMP for this particular piece:

Mirror your layer: Layer > Transform > Flip horizontally
Stars in background (bg) blurred, layer duplicated and mode set to "grain merge" (62% opacity): Filters > Blur > Gaussian Blur (15x15 pixels)
How to dodge: Set the brush mode in your paint brush tab to "dodge" and use the colour picker to chose the right colour you want to dodge

A great tutorial on colour choice and theory by purplekecleon can be found here: tinnu.deviantart.com/art/How-I…

Finished piece: tinnu.deviantart.com/art/The-C…

My collection of helpful art resources like tutorials, stock, brushes, textures etc. tinnu.deviantart.com/favourite…

I hope you'll find this helpful Let me know if you have questions or recommendations!