I suggest: (1) choose a tool/language/library you want to learn, (2) work through a use case and write a blog post about it to help the next person do the same, (3) consider how the README or docs should be updated accordingly.

Writing up your experience is often a useful trigger to create an open-source tool/library or modify an existing one. It forces you to consider how your own experience can be made useful for others.

Also read the source of tools/libraries you use. Often, gaps or modifications jump out readily.