Robin is right... but unfortunately learning a dead language is more challenging than living languages because you can’t find native speakers to generate personal sentences! Also, you can’t rely upon Google Images searches of Old Norse blogs. That means that you’re going to have to depend almost entirely on translated sentences, and basically absorb everything you can possibly absorb from those sentences. So you’re going to modify Fluent Forever slightly, as follows:
1. Do start with pronunciation and spelling. If those spellings look foreign, they’re going to be harder to remember. And if you’re using sounds that aren’t in English, even if the language is dead, then you might as well learn those sounds, because any time you’re thinking something like “Oh, that word starts with the L-like thing that I can’t really say and who cares anyway because it’s a dead language”, then you’re going to have a harder time remembering that word. If you need to simplify pronunciation then that’s okay, but you need to get to a point where you can look at a word and pronounce it reliably in SOME manner, and if your teacher says a word in class, you should be able to picture in your head how it’s likely spelled.
2. Learn enough picture words to get a feel for how they work, how Anki works, and, if you’re using them, how your gender mnemonics work. This might be 10-100 words.
3. Now, instead of continuing with picture words, jump directly into sentences. You want to have access to as many translated sentences as you can possibly find, and you’re going to want to understand how the grammar is working in those sentences as well as you can. Then dump them into Anki using the all-purpose flashcard model, and break them into their component parts (word forms, word order, new words). Make flashcards for EVERYTHING. Without access to native speakers, these sentences are basically ALL you have to go on. So don’t skip anything. You want to basically memorize every sentence you encounter in a class by breaking it apart into 5-15 flashcards and memorizing the answers to THOSE.
Then keep doing step 3 until you have a feel for the language. It’s all you have; you don’t get to go speaking or listening to TV shows or anything, so you need to milk step 3.