1) Level the boat.  Place a level under the pad of the boat. Adjust the trailer jack up or down till boat is level
2) Level the motor. Place the level on the cavitation plate, and trim the engine down till it's level
3) Measure from the ground to the pad, Write the measurement down
4) Measure from the ground to the center of prop shaft, Write it down.
5) Deduct the two measurements. You want the prop shaft 3 1/2" below the pad of the boat.
6) Adjust the jack plate up or down, paying close attention the water pressure and max. engine rpms.
7)On lighter hulls with low water pickups, running at a neutral trim angle is best.  To find the neutral trim angle, simple turn the ignition key on when you have set the engine at level. The needle will be pointing to a neutral position.  If needed mark the trim gauge for future reference.