If you can't figure out what you are doing wrong when firing your pistol, take a look here. This video tutorial will show you how to troubleshoot your handgun shooting. If you know about proper sight alignment and proper sight picture and proper shooting stances, you will be better overall. Breathing is key, so make sure you are breathing correctly. If you're hitting all over the place, you're looking at your target, not the front sight post of your weapon.
Remember three basic safety rules; always keep the gun pointed in a safe direction, always keep your finger off of the trigger until you are ready to shoot, and always keep the gun unloaded until ready to use.