The gojuuon chart: ten sound rows and five vowel columns
Every kana sits in a grid called the gojuuon. The first row is the pure vowels あ い う え お. After it come the k, s, t, n, h, m, y, r and w rows, each paired with the same five vowels. The y row only holds や, ゆ and よ, the w row is down to わ and を, and ん stands by itself at the end. That arrangement is where the figure of 46 basic characters comes from, and katakana follows exactly the same grid with sharper, more angular shapes.
Learners who try to memorise 46 symbols in random order tend to lose them quickly, because nothing ties one character to the next. With the chart, each character only needs two facts: its consonant row and its vowel column. Once か is known as ka, the characters beside it have to be ki, ku, ke and ko, and the only remaining job is matching the shapes.
One or two rows per session works well. Write the row five times while saying the sounds aloud, cover the chart, and try to reproduce the whole row from memory. The next session opens by revising yesterday's row before a new one is added. At that pace hiragana usually takes one to two weeks, and katakana goes faster because the sounds are already familiar.
The signal that this stage is done is easy to check. The learner can write out the full hiragana chart from memory in a few minutes and read a shuffled string of characters without counting along the rows in their head.
Learn kana by consonant row and vowel column, so every new character has a fixed address in memory.