Pretty sure all the learners find distinguishing these two pretty difficult, as well as ン (n) and ソ (so) which I'm sure you'll encounter soon.
Though, since ツ (tsu) is the equivalent of つ and I'm sure you know how it can also be used.
Speaking from personal experiences, encountering it in cases like the ones below made it really easy for me to remember it:
ツ was probably for me personally the easiest one for remember because of its usage.
It's just a matter of associations in my opinion. I still have some problems with them myself since katakana isn't used that much overall (at least, well, compared to hiragana), so you probably shouldn't worry about them that much. You're gonna master them all after a while anyway. Well, if it does help (even though you've probably realized it by now) those stand together since they are bent in the same way, and it helped me at least (and it still does):
ツソ (tsuso) シン (shin)
I don't know man, this just helped me most personally, so I'm not sure how it's gonna be with you but I'm glad if it did help a bit!