Well I play with my 4 fingers too (my thumb just for some arpeggios and slap) and here is my way, I wish it'd be useful for you:
I always(almost always) use my fingers in order with index(1),middle(2), stupid

(3) and pinky(4). Even though it was first very hard, I play triplets with my 4 fingers too as 123 412 341 234...
My second incredible invention

is when I'm going to one lower string I play with the finger which last picked in the higher string by carrying on the movement of my finger. (how hard to explain it with words as it'll take 5 seconds to show it) Ex: If I play with my ring finger on G string and passing a note on D string I play the next one with my ring finger too... OK if it's still not clear excuse me I can't do it better.
On the other hand I know a guy who uses his 3 fingers but in the reverse fingering order of mine beginning with ring finger, then middle, then index...
I was planning to prepare a video and make some money on it but here you got all my secret

(OK just kidding for the last part)