As a teen, I wanted to be a simultaneous translator and had aspirations of becoming fluent in seven languages (counting English). That never happened but I know a smattering of multiple languages and I know a bit about learning another language.
I never learned Farsi AKA the Persian language, though I wanted to and went through a chapter or two of EasyPersian.com and still have the link years later. In my teens, I wanted to become fluent in multiple languages and had a list: German, French, Spanish, Russian, Greek "and one more, probably something Asian or Middle Eastern."I've actually studied every single one of those languages though I've never achieved fluency.
When I lived in southern California, I sometimes watched the Spanish language channel with the English subtitles on because my German immigrant mother told me watching TV is how she learned English.
Link rot happens and I no longer have the list of German and Spanish resources I used to help fulfill the foreign language requirement of homeschooling my sons under California law. One of them chose German and the other chose Spanish.
My mother grew up in East Germany and took Russian in school. I can count to ten and I know maybe another dozen words. When we first began homeschooling in the middle of nowhere, as a hobby I was looking up Russian words online and at one time could recognize the sound associated with about half of the Russian alphabet, though I never learned to recite the Russian alphabet. I also took Classical Greek in college and the alphabets are similar.
Some thoughts:
1. Popular stories you are already familiar with can sometimes be found in your target language.
The original German title for Cinderella is Aschenputtel and while my son studied German, I had a link to a website with that story and others in bother German and English and I would print both off so we could compare them side by side.
2. It's enormously helpful to find audio recordings.
I used to have German and French Berlitz language learning tapes and played them while reading the lesson and practiced my pronunciation. Even if they use the sane alphabet, foreign languages are going to be pronounced different from your native language and you really need exposure to hearing how it sounds.
I used to know of a site where I could click on the Russian words and hear the pronunciation, which is how I learned the sound associated with half of the letters.
3. The written language and the spoken language aren't actually the same.
Native English speakers know the rules for formal written English for their school papers aren't the same as how they engage in casual conversation with friends, yet people routinely seem to imagine the spoken and written forms of another language are the same. They aren't.
I did use language tapes and did use written materials for helping my son study German, but I really learned German from relatives because my mother was German and I learned French in classes taken in high school and college.
I have an ear for German which I don't have for any other language and was reasonably fluent in conversational German at one time, though I can't really read and write it nor even follow the evening news in German which is more formal than conversational German.
I do okay with trying to read and write small snippets of French but struggle to follow spoken French and cannot really speak it. I mostly learned it in school and most of my exposure was reading abd writing it, not speaking it or hearing it.
So consider your goal. If speaking fluently is the goal, reading and writing it won't get you there.
4. Immersion is the best way to achieve fluency.
It gets on my nerves that Americans are criticized for only knowing English because I tried hard to learn multiple other languages and never achieved fluency.
When I lived in Germany as an American military wife, I mostly interacted with other Americans in English and when I did interact with local nationals, most of them immediately switched to English to practice their English with a native speaker. My German did improve while living in Germany because I carried a German-English dictionary everywhere and served as translator for my husband, but it didn't improve as much as I hoped it would.
If you can arrange an immersion experience, that's wonderful but the reality is most people seem to learn enough to be useful for their needs but don't really become fluent. I have tried to get over being upset that I'm not as fluent as I wish and just be glad I know a few useful tidbits.
5. It helps to get resources recommended by someone in the know.
A native speaker of Farsi gave me the link EasyPersian.com.