number your arrows so you know which one is which, then shoot again and keep track of which ones are hitting close and which ones are flying wide. If you notice its just one arrow consistently messing up your groups then you know there is something wrong with the arrow. If that doesn't work you might want to consider trying another type of broadhead. You also might want to have a bow shop look at your bow and make sure everything is lined up right. If all that doesn't work just keep practicing. Make sure you are practicing good form too, don't just stand there and fling arrows, you'd be surprised how the slightest slip up in your mechanics will cause you to miss.