Use a benchrest (with your hands holding the gun resting on a sandbag, bag of rice, etc.)
Start at about 30 feet, slowly squeeze off your rounds. Shoot 4-5 then assess. (The idea is to make sure its the gun's performance that's being assessed, and not your shooting technique.)
Adjust your sights with a brass punch or sight pusher. Move the rear sight in the direction you want the point of impact to move to.
If you're getting good results at 10yds/30 feet, you can move out to 15-20 yards. (Handguns can be used for greater distances, but generally, if you're going to use one in self-defense, its very likely that it'll be a lot closer than 20 yards.)
If you find, as you move out to 20 yards or so, that the gun is shooting too high or too low, either go to a different weight bullet (heavier = higher point of impact) or get CZ to send you a new rear sight, that is higher or lower. You can tell them how far you're off at a specified distance.
