This is pretty easy for me; if I'm flying line of sight (LOS), the black dot on the front from the camera is pointing away from me. Also, on my Inductrix Pro, there's two different shields - a blue one and a black one. I put the blue shield cover on it, so that if I see mostly blue, I know the drone is facing away from me, and if I see mostly black, it's facing towards me.
On the Inductrix FPVs with the Red or Yellow scheme, you're going to see the black of the camera housing/lens if it's facing towards you, and red or yellow if it's facing away.
Another easy way to tell is to get some extra props in multiple colors, and put two props of one color in the front, and two of a different color in the back.