I mean, there's always the radar. if you're confused just take a quick peek at the radar and relate it to what you see around you. if there's a guy in front of you and he pops up orange on the radar then he's the enemy.
I say this because there have been times where i've been confused too, but when i use my radar it helps me make that quick differentiation and then i'm all good.
I also like the fact that i get to see my heroes in black and red or black and green, so i'm not really for changing it to "us Blue, them Red" every single match.