Illustrator, to me anyways, is that best friend that you wonder why you hadn't gotten to know sooner.
It's painful to think about, but when I was first getting into digital art, I used to create paths in Photoshop and use the "stroke along path" option for the brush. Horrific, I know. But growing from there, I learned about Illustrator, learned the power of vectors, and have since learned the error of my early ways.
And how time can change things. In the span of three years, I went from creating the image on the left to that on the right. While learning is never truly over, I now feel I have learned enough about Illustrator to start working on refinement, experimentation, and building the experience of pushing the limits of what I think I can do.
And the best part of trying different styles, experimenting with different techniques and looks, I still get to learn about Illustrator and the process. The fact that I can look across the various vector pieces I've worked on recently and see the lessons I learned from each makes me excited to dive into the next project.