I choose my zero as the distance where the peak of the pellet flight forms a tangent with the optical axis of the scope. For a typical FT set up that is something around 25 yards, depending on mount height.
Then, all my dialling is in the same direction; short targets and long targets, I always dial upwards. After each shot I return the top turret back past the zero point then bring it up to zero. The idea is that I take out any backlash in the turret.