Barry Farber’s How to Learn Any Language is a great resource for language learners to learn how to learn a language as well as general motivations for doing so.
A lot of the motivations still hold true today, including the value of Americans specifically learning a language (because no one expects them to do this). However, a lot of the methods are suggestions from an earlier time, such as buying a subscription of a foreign newspaper, ordering physical flash cards, etc.
This post aims to provide alternate suggestions which have made these supplies more portable and accessible for me. Hopefully they will be useful to you as well.