Solenoids engage regardless of the direction of current
flow in the solenoidal field and, therefore, the low current
connections are not polarity sensitive unless they are specifically mechanically designed to connect with the engine
block which must be negative (unless you are unfortunate enough to have a positive common engine
, not likely though).
The high current contacts are also not polarity sensitive and may be connected either way if they are mechanically the same. So, all you have to do is identify the solenoidal low current terminals by their "wimpy" small size and identify the high current starter/battery current terminals by their comparatively large size.