What is the best way to improve your language skills?

What is a good way for heritage language speakers to improve their language skills?

• Especially if that heritage language is primarily oral.

• Answer:

  Speak it. Teach it. Go through the process of making it not oral. Who among us understood the difference in "much" and "many" before we first taught it?  Who could tell the difference between a spanish B and a spanish V before it was written down?  You do not speak good English well if you haven't spoken it a lot, studied the grammar, and read a lot of books.  (Let's start with why you don't like the phrase "good English well.") Heritage languages will disappear entirely and irrevocably unless they are preserved the way a famous painting is preserved: 1) through appreciation, through marketing it and through making a million copies in various forms, 2) by teaching others to appreciate it, and 2) by painstakingly archiving it by professionals.  Why else do we not consider Latin, ancient Greek, or ancient Hebrew "heritage languages"?  Answer: because despite few to no people speaking them, they're not considered endangered because they're everywhere and always in demand.