I decided to test my skills, and do some texture spheres. I think it is a great way to improve your skill, because you have to think not just about the texture, but how it looks under different amounts of light. I feel it was a very steep learning curve, and I didn't make these as well as I would have liked.
Any feedback on how you would improve some of these would be well appreciated, and will help me in the future when I try this again.
If you want to see my process while drawing these, and hear some of the things I liked and didn't like about these, I invite you to watch my video : https://www.youtube.com/watch?v=V-zNfMQXtLM