Here are some pages about tutorials and articles that helped me over the years. I don’t verify those links often, so they could be down or redirect to unwanted sites.
Verification date: 9 June 2019 (firefox+adblock)
Make a Realistic Star Field (for Photoshop, small chat pop up):
I learned a lot with this tutorial in Photoshop(by Dianae):
Some nice manga tutorials here, especially for coloring:
Other abstract wallpaper designs:
Space designs in Photoshop. I tried a couple of them:
This site is pretty big in content, but what I really like is the tutorials.
Ocean tutorial: http://polygonblog.com/3d-water-the-ocean/
Here are some stuff, some working, some not:
If you need to draw a human in a position, this is a virtual dummy:
FREE High Quality Textures for personal and commercial use