I take notes on paper while studying the subject, then when I'm done I put the essential concepts or whatever I want to memorize into cards in Anki via my compu

I take notes on paper while studying the subject, then when I'm done I put the essential concepts or whatever I want to memorize into cards in Anki via my computer (I usually avoid adding them on my phone, it's slower). It is a slow process, but for getting new ideas to stick, I'm not sure that's a bad thing. I don't usually bother with preexisting decks. If you’re building your own from your own study, it almost guarantees you actually understand what you're trying to memorize.