Did you know you can often tell a verb is transitive or intransitive by looking at the end? A transitive verb often ends on ～す (する do) or ～える (able) and intransitive often end on いる or ある (existence).
It doesn’t always work and there are exceptions, but if you don’t know I noticed you often guess correctly if you keep this in mind.
It helps me a lot, so I thought to share this info. 
could you share some examples? 
You find its pairing and it will always be one over the other, unless it’s a ～く～ける pairing, in which case it’s based on vibes as to which one is the main definition/original definition/common definition, which will be ~く, with ～ける being the secondary transitive/intransitive meaning.
Another weird one would be ～する, but that’s better left as its own thing.
There’s also a lot of good info about transitive/intransitive pairs in this thread:
汚す : To make something dirty
汚れる : To become dirty
壊す: To break something
壊れる: Something breaks
開ける : To open something
開く : Something opens
閉める : To close something
閉まる: Something closes
起きる: To wake up
起こす: To wake someone
回す: To turn something around
回る: Something turns around
直す: To fix something
直る: Something gets fixed
etc…
ohh, i thought す meant transitive and れる or る meant intransitive, that was my guide… good post!
Looking at all the pairs and all the exceptions to every rule can for sure make it look overwhelming, in my opinion this is one of the most difficult parts of Japanese to nail down, but when you’re reading or listening to native material it’s almost always very clear through both context and the sentence structure, since intransitive and transitive verbs are used in different ways. When speaking or writing it is necessary to remember but when you’re just trying to get meaning across, I haven’t found it to be a problem very often, people know what you want to say.
In fact the only time that this gives me grief is when I’m messing them up on Wanikani because you get no context and no leeway for mixing them up lol. So it may seem overwhelming, but in practice, it really is mostly vibes based!
Recalling of simple sentences, emphasizing on particles (が, を, に, etc). Also, both reading/listening and speaking/production can be helpful.
In a way, flashcards are more about recalling than finding a best way to remember. Meaning can be rephrasing from understanding. Recalling failure – just postpone and review more later (if something deems more important).
Thar’s a very good question. The most useful and clear explanation I ever found was the one from the legendary Cure Dolly YouTube channel: