If you're going to own a gun, practice. Get used to loading it, disassembling it and reassembling it. Learn what issues that specific gun has. Learn how to unblock a jam with that model. Ideally you'd be able to take it to a range and shoot it regularly but this isn't always affordable or feasible. There are exercises you can do at home. Develop habits of checking to make sure the chamber is empty whenever you plan on putting it away or not using it, unless you want it loaded for a home invasion or something.

In the military they make you spend a week doing the most mind numbing exercises before they ever let you fire a round. This includes practicing your shooting stance, learning to keep the barrel steady, and how to squeeze the trigger without ruining the shot. It's all available online in YouTube videos. Look up different ways to hold the weapon. For example, I liked to wrap my strap around my wrist when aiming a rifle because I felt it gave me more control but everyone else had their own thing.

An example of an at home exercises is to balance a washer flat on the tip of your barrel and learn to squeeze the trigger until it clicks without dropping the washer off.

Disassembling is fun to do and it's important. You likely won't ever need to just disassemble your gun in the middle of a fire fight but hopefully you've done it enough that you know where every little gun part is in case you need to trouble shoot an issue.

Anyone can buy and use a gun. They're pretty straight forward. You load a magazine, chamber a round, point and squeeze and that's it. You could get killed by a child with a gun. But if it ever came down to a situation where you and your enemy both have guns, you want to be the one better trained. If you have a shotgun for home protection, you don't want to waste time figuring out how to cock it and aim it in the middle of the night when you're groggy. You want it to be muscle memory.

I'd say you know you've been practicing enough when it's not fun to use them anymore. When you get to the point where shooting a target is boring or you no longer take your gun out to play with it, you've probably got a good handle on things.