Common Question
Shotty's take some work to use skillfully.
Dave has it right. Get something reliable, then Buy Ammo, Use Up, Repeat.
COMMAND of a shotgun will take some time. Some take to them right away, for some it takes a little more effort.
There are WAY TOO MANY "uber-tactical" models out there. Marketing focus does not success guarantee. Nor does it nullify usefulness either.
I'm a Mossberg fan. They fit me. I have short arms so I put a 12" Length of Pull Hogue Stock on mine. You can't optimally operate a shotgun that fits you poorly any more than you can win a footrace with shoes that are way too big or way too small.
I'm a big fan of Good sights or an Optic on a shotgun...I prefer Ghost Rings, but I've used the EOTech/Bushnell sights also with good success.
Some ranges will rent a shotgun to you. Might not be a bad play to get a sense of what you like and don't like.
The shotty should be comfortable to handle...when in doubt, go with something a little lighter. Over time, you'll be able to handle something a little bigger. This isn't about machismo, it's just being practical with this platform.
A good condition used shotgun (no disagreement with Remington/Mossberg as candidates) may be a good way to get started.
Again, as Dave mentioned, it's about developing a shotgunner (decent reliable shotty assumed) more than buying the ultimate shotgun.
Unlike some firearms for defensive use, you don't have to spend a bundle. Even for those of modest incomes, the value of getting into something reliable (even if replaced later) may outweigh the benefit of deferring experience by buying "the best" shotgun out there. Reliability, initiative to practice, discipline in staying with it, curiosity to ask the right questions and seek out instruction. These will help you become a capable shotgunner that can defend hearth and home. The Shotty is merely the reliable tool in your hands.
Good luck, and Keep Safe,
CZ52'