The skills of language: speaking, listening, reading, writing,
But what helps you learn those skills?
Research (afaik) says people who can tolerate ambiguity have an easier time learning to communicate in a foreign language. But described that way, that's an attribute of the person, not a practicable skill. Is there a codifiable list of practices and skills that it would behoove a student to gain if they were interested in gaining language skill.
That's to say, if you were going to run tutorials for language students in which they would practice learning a language, obviously they'd practice the language itself a bit, but they'd also want to practice learning the language too. In that case, what would they practice?