For vocabularies, as well as Kanji, there is indeed a trick to initial memorizing, without Anki. Though, it was a while since I last did the trick (with Kanji, which are sometimes harder to remember).
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I made several meaning mistakes 
, but then, writing the meanings yourself is already a translation practice.
Thinking about it, this is similar to getting a tabular pocketbook, and having a cardboard to shield the first column. Colored rows are for the sake of doing 10 at once, (then check 10 at once). It’s a little surprising how easy it is to forget.
It is important that meanings are personally written, and made different from other similar words. Otherwise, take notes of whatever comes to mind first – which includes mnemonics.
Well, this is only for initial short term memory. For middle term / long term? Simply continuing to read the genre of your interest should do the trick.
For grammar, I really don’t know how to advise, but have heard about Particle mining. I also have a reference book for particles. Otherwise, composing a sentence regularly should help; but there are basics, and paths to pave, just as far as a workbook (from a textbook).
Recently I tried bunpro.jp, and made quite a lot of wrongs. Try composing, and realize that you make mistakes probably would help well with grammar. But I can’t say I am committed to this app yet 
I have watched vanilla’s 2-hour advice, which I agree with most of it – you don’t need that many core vocabularies, but there are indeed so many vocabularies. So, mining and having fun always.
Also, there aren’t only vocabularies that can be mined.
I have to admit that me remembering Hiragana was half about listening, and associating sound with text. (Katakana, however, largely came from drilling a loanword list.)
Of course, I tried remembering all Kana before that, but I can’t say I remembered them well at all.