A friend of mine moved to Japan about 10 years ago and has spent a lot of time solo developing his site, Kanpeki Study, for efficiently learning Japanese kanji and vocabulary in bitesize, daily chunks. I'd be doing all his effort a massive disservice if I didn't mention it - hopefully turns out to be a good fit for you 😄.

Busuu is fantastic. Gets you to think through the words and gets your feet wet with hiragana/ katakana right away.

Take a look at this guide, it's what I've been following https://learnjapanese.moe/guide/

Essentially, use Anki to study vocabulary in bulk, and use grammar guides like Tae Kim's. And spend a lot of time reading and listening to real native content

It's worth noting that Duolingo has always been considered.very bad by most of the Japanese learning community.

Repetitive yes, but that's the point of Rote memorization. Duolingo should be a tool in the toolkit but not the only one.

Renshuu is Japanese specific and has been really enjoyable for me. Has a community of people contributing fun mnemonics (eg. "WArio's big fat dumpy" for the hiragana of Wa) and a clearly caring developer.

I used Wanikani to learn most kanji.. textbooks and actually talking and listening to Japanese ppl for the rest.. still not that good but can converse. Much better at reading. Recommend watching japanese shows w japanese subs once you get to that level.

LingoDeer is the closest alternative to Duolingo, you might want to give it a try

Around when I was getting started with Japanese, I studied around 1k of core vocab with Anki. Not that it wasn't repetitive. The thing with learning language (IMO) is that it's a lot more fun and easy to stick with if you find something enjoyable to practice with. Maybe in your case that's reading really simple stories or something like that. BTW, I'd also recommend Cure Dolly for grammar.

Assimil courses are always a good choice