Here’s the best method: put your ammo in the ammo pouch, then grip the pouch with your dominant hand, between the thumb and forefinger (try to hold the pouch where it contacts the ammo). Draw the bands back with the slingshot pointed at the ground, the same way you would hold a gun. This way, you shoot into the ground if you accidentally fire it.
Lift the slingshot toward your target sideways, so it makes a sideways Y. DON’T hold it with your hand directly in front of your face: if you lose your grip, you’ll punch yourself pretty hard in the face (I’ve done it).
Instead, aim with the pouch pulled back to your cheek below your shooting eye. Sight straight down the top band and align the top edge of the fork with the bullseye.