If you want to overcome a trigger jerk or a flinch, the Wall Drill is the perfect way to fix these issues. This drill is all about trigger control AND it's a dry fire drill, so you can do it anywhere it's safe to work with your firearm.
Before performing this drill, make sure that your gun is unloaded (double check) and there is no ammunition in your magazines or anywhere in the room.
To perform the Wall Drill, find a safe direction, bring your (unloaded) gun up to eye level, align the sights, then place the muzzle about an inch from the wall. Once you are in place,"fire" a shot while focusing only on the sights and pulling the trigger straight back. Repeat at least a dozen times per dry fire session.
The goal is to manipulate the trigger without upsetting your sight alignment. If you perform this drill on a regular basis, you'll see a big improvement in your accuracy!