You have to experiment and decide what works best for you. Personally, I find reading a book in the language I'm learning the best. That, combined with YouTube videos.
I have taught myself French that way. I'd especially recommend dual language books, where you have the French on one side and the English translation on the other. They have done Flaubert, Proust, Maupassant, etc. You can also buy English-language classics with the French translation on the other side. Don't rush. The key is keeping at it. Just do a little every day. I have dual language copies of Oscar Wilde's Portrait of Mr W. H., D. H. Lawrence's short stories, and Virginia Woolf's Mrs Dalloway. I'd rather try something lighter like P. G. Wodehouse, or even the Narnia books, but I don't think they've been turned into dual language editions (then again, Wodehouse is probably untranslatable.)
The infuriating thing is that you think you are making amazing progress and then suddenly find all your confidence knocked out of you. I actually read a few pages of Proust a while ago (Proust!!) and found I could understand it. I was buzzing. Then I tried to hold a conversation with someone in French and mumbled and stuttered and hadn't got a clue. I find the same with reading. Sometimes I'll pick up a French book, open it at random, and find I can read an entire page. Then a week later I'll be in a different shop, pick up a crappy detective novel, and struggle to get past the first sentence.
God how I wish I'd concentrated at school. Education really is wasted on the young. I had such brilliant, keen French tutors, and I just sat there in a sulk ignoring everything they said.😕If I was 16 today, I'd do A Level French and A-Level Italian (or maybe Latin) and work like a slave.