Help with actions relative to safety
As BugeDude implies, consider the holster itself a "safety". As noted it should fit the firearm properly and cover the trigger and retain the firearm even with strenuous movement.
Your finger is another safety. It should not be on the trigger until you are pointing at your target.
Practice with your firearm unloaded and the firearm pointed in a safe direction safely drawing and pressing out towards your target then reholstering with the specific goal of reinforcing muscle memory to keep that finger off the trigger. Don't rush. Did I mention keeping the finger off the trigger?
As noted, modern firearms won't fire unless the trigger is pressed. Your proper holstering and finger discipline will prevent the trigger from being pressed.
And remember the four rules:
- Always treat the firearm as if it is loaded.
- Never point the firearm at anything you are not willing to destroy.
- Keep your finger off the trigger until you are on the target.
- Be sure of your target and what is beyond it.