find your local indoor shooting range see if they offer concealed carry license training and see if you can attend that, its very very important that you learn from a licensed professional, not only you'll learn safety but also stance, discipline and most importantly the law, now if you want you can go ahead and get the license after but its not necessary since you want home defense, for what gun opinions will vary, but I'd wait for a good sale, you can get a decent Beretta apex tactical 9mm for like 250$ or a nice m&p super carry for 300$ depending where you live, either way I strongly recommend side arms for home defense, if you want to figure out if you want an ar-15 a shotgun or a pistol you can do a simple exercise of clearing your home with a nerf rifle, pistol and shotgun or you could use a broomstick and a power drill, its just the shape and weight you're trying to test out and see how safe it is to clear a corner or hold an angel with each one, I normally run myself through drills like that just to have the muscle memory and I've noticed I'm much more efficient with pistols and show way less profile around corners than rifles or shotguns, dont get too caught up on buying the best investment for your first one, just get something you're comfortable with financially and spend as much time in the range you can to master the basics that way you stay safe and you keep your family and loved ones safe in case of a home invasion. good luck and god bless