I agree. Definitely don’t just use Duolingo. It’s not even meant to be used as a sole learning source. Use some kind of flash card memory thing like Genki. I found an app called Kanji Teacher, but I think Genki is the better version. KT has only one set of flash cards but with Genki I think you download new ones and make your on.

I will probably switch one day, but I like KT’s writing practice cards and the learning history tracking. Duolingo barely teaches you to write the letters or kanji, so handwriting them, especially by making myself write furigana for new kanji that I learned rather than spelling it out in romaji, really has been helping me remember hiragana. One of my goals is so learn simple Japanese calligraphy, so I really like the writing part.

Katakana I’ve found to be a little harder, but I hear that’s common. Mostly I stumble on the spelling of things in Katakana and getting some of the extremely similar letters confused. Especially シツソンノ at first, but some of those letters are so extremely common that I mostly have them down now. I still have trouble with ウフワヲラテナ now.