I'm sorry for such a late reply! Thank you, I'm really glad that you like it!
Most of what I learned I learned from "How To"s and Coloring Tutorials on deviantart. They can be really helpful. After learning basics from those a lot of it is trial and error and developing your own style and ways of doing things. One big thing that I felt helpful is using as many layers as you need to make yourself feel comfortable. Then sort your layers into folders for different parts of the picture to keep track of them. If you separate things into layers they can be easier to fix later, and then the more you learn and develop your skills the less layers you will need.
I hope that helps a little. I really suggest looking at tutorials on deviantart, there are a lot of fantastic ones.
She should! Very good colors and details, I love her fins. The hair is splendid, about the only conceivable issue would be that she looks rather the waif--but I trust the Favorite conveys the depth of my admiration?
Thank you! I agree, she does look very thin. It's her character design, but I think it makes her look thinner that I painted her in "3D" instead of in 2D. All the same, I'm really happy you like it and thank you for the favorite!