Q: “What should I work on?”
This isn’t always easy to answer specifically, because a great deal depends on the skills and interests of the person asking. But there is an easy general response:
A: “Solve a problem for yourself.”
I’ve found that the developers not asking that question tend to do exactly that. They have a need, see no available solution, and jump right into solving it for themselves. Often enough, that tends to work for others as well.