First, find a good school and get trained. I'm sure there is more than one in your area. Not only do you need to know your weapon inside and out, including failure drills, maintenance, and marksmanship, but to understand tactics and -- most importantly, especially in your state -- legal issues.

Second, find a really good hiding place for the gun. When the authorities come to take it from you, claim it's elsewhere. If it's legal to loan it to a relative, tell them you lent it to that legal relative, who happens to not live in your hometown.

Don't leave home with it.

If you leave home. Leave it hidden. And locked up. (Because nothing is EVER hidden enough. Any thief worth their salt already thought of anything you could.) And, to be safe, take a key component with you, so if it is stolen the so-and-so doesn't get anything useful.

If you leave home with it, you'll need to transport it legally. If it's visible, it will be confiscated by the authorities. If it's loaded and carried concealed on your person, not only is it useless for defense, but it's going to get you in jail in NY pretty fast.

Plan on investing many times the price of the shotgun in training and practice ammunition. If that's not in the budget and you don't have prior training, then skip it.

If you're going to get one with no training anyway, get a reliable auto like the Mossberg 930, because it's pretty easy to short stroke a pump under stress.