So you can indicate zero on your left hand by not touching your thumb to your hand at all.

Then you indicate 1 by touching your left thumb to the first section of your left index finger. You count along the sections of your fingers until you reach the end of that finger (should be 3), then moving to the next finger, with the first section of your middle finger being 4. Moving in this way, when you reach the the last section of pinky, you should be at 12.

Then you lift your thumb off your left hand completely as you touch your right thumb to the first section of your right index finger. You have indicated 0 on your left hand and 1 on your right. This is the equivalent to 13.

Continuing this way, you can indicate the multiples of 13 (13, 26, 39, etc) as the sections on your right hand (with 0 indicated on the left hand). When you reach the last section on your pinky with your right hand, you have counted to 156. (And then you can count an additional 12, but that seems to be something we’re clear on).

I’m actually unclear how you’d get multiples of 12 out of this? Do you skip a section of a finger? Or, like, as you touch the last section of your first pinky, is that when you touch the first section of your other index finger? That latter option feel redundant, and so I’m not clear why that approach would be advantageous?

Edit: trying clarify by indicating left and right hand (as I count with this method) instead of 'first" and “other” hand (to be more general to how others might do this).