Rules for adjusting sights.
To RAISE the point of impact, DECREASE the height of the front sight.
To LOWER the point of impact, INCREASE the height of the front sight.
To move the point of impact LEFT, move the front sight to the RIGHT.
To move the point of impact RIGHT, move the front sight to the LEFT.
OR
To RAISE the point of impact, INCREASE the height of the rear sight.
To LOWER the point of impact, DECREASE the height of the rear sight.
To move the point of impact LEFT, move the rear sight to the LEFT.
To move the point of impact RIGHT, move the rear sight to the RIGHT.
Some firearms may require a combination of the above. For example, the rear sight may allow adjustment ONLY to the left and right while the front sight ONLY allows elevation adjustments.
Never adjust the sights unless you are SURE that they need adjusting. That means that you need some level of confidence that the bullets aren't hitting where you're aiming, and that it's not your fault. This is one of the hardest things about sighting in--especially for newbies.
Never adjust the sights based on a single shot. You should shoot several shots and then adjust the sights based on the rough center of the group.
Make sure that you know which direction you are adjusting your sights. Some sights have screw adjustments that are not marked. Before twisting on the adjustment screw, you need to understand what's supposed to happen. Sometimes the adjustments are marked with a convention that is not common in the U.S. I have one European match airpistol on which the sight adjustments are marked backwards to the way I am used to thinking.
Be VERY careful about making permanent changes to the sights (like filing the front sight to decrease its height). Different types of ammunition will shoot to a different points of aim. Before you decide to make permanent changes, decide on a type of ammunition that will satisfy your needs in that firearm. Even then, you should make only make a very small change and then test the firearm again to make sure you don't go too far.
Remember that sighting in a firearm can only be done at ONE distance. If you adjust the sights perfectly at a particular distance, it will shoot above or below the point of aim at other distances. It's not usually a large difference for relatively close ranges (as with handguns), but it's worth remembering.
If you're drifting sights (moving a dovetailed sight using a punch or a press) you should mark the position of the sight before you start the drifting process so you can tell if and how much you have moved it.
Ok, someone else can take it from there...