when i was learning letters i wrote them down with a funny mnemonic and thinking of it through out my day and trying to put names and stuff into Japanese. basically just use the letters in your everyday life.
Usually when you learn hiragana and katakana they give you mnemonics in grammar you can write it down, kanji they have mnemonics too, and for words sometimes they sound like English, example, coffee is コー匕ー ( co-hi-) an they sound the same just like jacket, stop, laptop, etc. For words that don’t sound like English (if your studying by English) then make some mnemonics (example, へや which is room apartment and when you see the words it’s like や looks like a person and へ looks like the door to the room, chamber, apartment, flat or pad
I always practice writing when I try to remember new letters. I find it sticks to my memory better when I associate what I see and read with a physical movement (writing). When it comes to kanji, I try to visualize the character it portrays, or connect it with something I like, such as a memory or a song. Sentence mnemonics help but I find it harder when it comes to memorizing kanji since I tend to get tunnel vision and remember the mnemonics instead of the actual character.
Everyone has different studying techniques so what may work for me may not work for you. You’ll eventually find your own way as you try different techniques. Good luck!
