I went to an interesting talk once at the Boston Python meetup, where a guy figured out how to order sentences so could learn them in an order where you already knew the "other" words in the sentence. Basically, making a directed graph of vocabulary. He was doing it to learn Latin, but you could do it for any language.
Goes from zero to extremely complex Latin. Whole book is in Latin, no translations.
https://www.amazon.com/Lingua-Latina-Illustrata-Pars-Familia...
The only requirement is knowledge of orthographic alphabet and how each sound is produced. Latin, fortunately, has very simple sounds compared to English or Swedish.
It took me about 2 years to go through both parts and I was amazed at how easy the journey was. Could speak and write Latin fluently without issues.