So, there are almost as many paths to get work as there are people trying to break into the industry, but in the spirit of sharing, I'd like to point out that one of the most in-demand jobs in the 2D cartoon industry is background layout painter....even better, studios tend to hire junior people to do this! Characters are *important*, most design goes to someone tested, or at least someone they know in the office. Backgrounds, on the other hand, are gone in a flash, and even a 10 minute toddler's show frequently has 150+ BGs per episode.
Here is a technique that helped me prepare for the industry. I got the idea from looking at matte painting, something called "plate extensions." It's where you take an existing environment, and paint on "extensions" on the sides to make it wider and meet the needs of the film. In a cartoon, practice environment though, try this: Screencap a hi-res shot from a cartoon in a style you'd like to work on. It will probably be framed at 16:9. Extend the sides to 2.35:1...or turn it into a pan shot, either up or across. Now paint the rest of the new blank parts to match the existing screencap.
For me, it's like a master copy, in that you have to pay attention to strokes, values, edges, texture and all the rest...but you still get to make stuff up! Also, because all the core information has been set, this is much faster and easier than painting something purely from scratch.
Here are a couple of examples I did several years ago when I was starting out.
Doing one of these a day will help you learn the styles of the shows you want to work on, and AS LONG AS YOU EXPLAIN YOU DIDN'T MAKE THE ORIGINAL they are good to show studios to show you can vary up your style.
So, if you're looking to mix up your practice, or, if like me, you get bored even thinking about master copies, maybe give one of these a try!
Hope you found this helpful, thanks for reading! Please share and help me reach more people!