Probably the most important aspect of learning and improving over the course of my career is attributed to having a go-to subject. This helped me focus on what's important and that's technique. Remember to keep you subject very simple as mentioned in the tutorial. Over time you will see this evolve as you expand on your arsenal of painting skills. Be sure to track this evolution. I keep a file of cow paintings on my computer. My first cow painting was in 2004 and I have added two, to three cow paintings every years since that first one was created. It's truly amazing to see where they started and what they have become. And they're still changing after all this time.