Hold the syringe vertically, outlet up, and draw in a little more air. Then tap the side of the syringe to dislodge the air bubble on the plunger so that it rises up to the outlet, then expel the air by slightly depressing the plunger. It isn't really necessary, though, since the amount displayed as the plunger moves does indicate the amount dispensed, but if you are uncomfortable with that, use the vertical syringe trick.