There are many great tips above too!!!
Cheap teaching method I used to use to help new shooters.
You need 2 1x4" boards....... The first time you place a single board in the vertical position and just concentrate on keeping your shots inside the 4" width and feel free to shot anywhere up and down the board...........
The next time you place a single board in the horizontal position and feel free to move your shots left and right...........
Those two exercises will get you used to a 4" wide / high target...........
Next step put up the boards together horizontal and vertical and concentrate on the 4" center
The vertical board helps with front sight alignment and the horizontal aids with the rear sight.
Shooting a pistol is exactly like playing a piano at Carnegie Hall......... Practice..... Practice........ Practice.
BTW since I used to run many ranges I am obligated to mention hearing and eye protection