A meta-skill is a practical knowledge that applies to a variety of fields. They are universal and help to quickly get better in any area. Learning how to learn, or meta-learning is one of them. It is a key skill for self educators and life-long learners. Such people are able to master different topics faster, and the more they learn, the better they get at it. Meta-skills as any other skills demand practice. You won't become a great learner or great writer after one essay on "how to write" or "how to learn". You can't master meta-skills because they don't have a horizon. Some people are better than others at learning or they even have a flair, but they always can get even better, reaccess their methods or unlearn.
That's the main challenge of meta-learning. You can days and months on learning how to do X, but don't practice actual X. It can be learning, writing, note-taking, playing music, or anything. How-To guides help, but they won't make you good at X. They can give right directions, tips and popular techniques, but that's it.
Meta-learning makes us better learners but we can easily overdo it. We should understand how to balance between learning X and doing X, learning X and learning how to learn X. All these are important, but each of us, life-long learners, should know the balance and reach the harmony in self-education.