I don’t know if this helps, but it’s you look up the source kanji on the Wikipedia ‘Kana’ page, you’ll realise that there are a lot of overlaps between hiragana and katakana sources. That means it might take you less effort, especially if you know those kanji already (or at least something similar). Here’s an example: つ and ツ both come from 川. If you know the correct stroke order, you’ll realise つ is just a linked-up version of ツ with the bumps smoothed out. That’s one of the commonly confused katakana down. Same thing with そ and ソ: the upper ‘7’ in そ is just a linked-up (cursive!) version of ソ. That’s another one down. し and シ are the same. That leaves us with… one commonly confused katakana: ン. That one doesn’t share its origin kanji with its hiragana counterpart (ん). But what are you going to confuse it with now that you’ve learnt all the rest?