I am hoping to learn multiple languages (specifically, French, German, and Russian) in the near future, and I was hoping that knowing some linguistics would accelerate the process.
1.) What are some topics in linguistics that I can study that would help me learn multiple languages?
2.) What are some textbooks that are well-suited for studying the topics in question 1? (Note: I know there has been several textbook recommendation questions in the past (such as this). My question differs from these questions because it is focused on language acquisition.)