I learned German in several frameworks (e.g. Goethe institut). Still, as reinforcement, I focused on finding the best way to use my time for self learning.
After experiencing different methods, I decided to use flashcards. These days, with the iphone, it is quite easy to use "digital cards" rather than paper ones. If you have a good app (e.g. ANKI), then it will adapt according to your learning pace.
As tech is significant to the method, it is also very important to have the good content in the flesh cards.
for this, I used the following website:
https://fluent-forever.com/method/
(I used it before Mr. Wyner became commercial and went to applications developments adventures).
I bought his book which is very useful in giving ideas about creating flash cards and their content.
I hope this info is useful