The shooting habit that’s probably the the most destructive to shooting accuracy is flinching- that is, unconsciously reacting before the shot is fired. This is most common with loud and high-recoiling firearms, but it’s pretty common with airguns as well, especially with shooters who who don’t have firearms experience. Luckily it’s pretty easy to cure.
If you find that your shots always string out to the right (for right handed shooters), or that you close your eyes when you pull the trigger, or that you repeatedly jerk the trigger instead of squeezing, you may be flinching. In the case of firearms, the general advice is to alternate heavy and light loads, or load a revolver with a mix of loaded and empty cylinders. With an airgun, of course, you can’t do that. But the low velocity of airguns (relative to firearms) you can do something that’s impossible with firearms: You can watch the pellet.
To do this, pick a heavy pellet- the 10.5grain Crosman Premiers, or Beeman Crow Magnums or Ramjets come to mind- and shoot outdoors at 20-30 yards, using the gun’s iron sights. Side lighting helps.
Concentrate on watching the pellet from the moment you can pick it up leaving the barrel until it hits the target. At first, you won’t see it at all. Then you’ll catch a glimpse, and eventually you be able to see it for a major portion of its trajectory. And by the time you can do that, your flinch will be cured.