Once you learn the elements of good form, how well you shoot depends on two things: your technical proficiency, developed through practice, and mental focus, developed by learning to tune out distractions. These are two different and mutually exclusive things: improving your technical proficiency will not improve your mental focus, and improving your mental focus will not improve your technical proficiency. Improving your technical proficiency will raise the bar of how well you can potentially shoot, and improving your mental focus will allow you to come closer to reaching that bar on any particular day.
Your first 3D shoot adds a new load of distractions, compared with shooting alone or with a few friends. If you shoot enough 3D shoots, the distractions won't be as bothersome. If you study mindfulness, or methods of expanding your awareness and focusing your concentration, you might be able to reduce the distractions to a level even less than when you shoot alone or with close friends. The potential for improving your performance when performing under pressure is probably greater by increasing your mental focus than by increasing your technical proficiency, although of course you should endeavor to do both.