I've seen beginners pull their triggers in the middle of transition from being holstered to ready without really aiming. I have a feeling many watch videos of Youtube ISPC shooters that draw and shoot amazingly fast and feel they are able to replicate it on their own - leading to doing the same at games.
Practice drawing your gun at home slowly and taking time to aim before you shoot. The time taken to aim should reduce gradually instead of immediately as you get used to where your BB's land in correspondance to where you point your barrel.
The key is to not rush anything, and stay relaxed throughout the entire training process.
Long story short: Take the time to steady your gun before you shoot. Shooting while in the process of drawing will cause your shots to be extremely inaccurate - despite what you may feel you are capable of.
Age Verifier - Unionville and Markham.