How can I puppy-proof my house?

Think about what a dog could get into. You’ve got to think of it from that aspect and perspective, like the viewpoint from being a couple of inches off the ground like that of a young puppy. They're going to see what's in front of them. They're going to find food on the floor. They're going to find trash cans that they can reach up and knock over. They're going to find anything they can get their mouth on and try to chew it. So you might want to invest in a nice kennel or crate—some place that you can put them in. And not as punishment, but let that be their normal domicile when you're not there. So at night, when you have company over, when you're not home directly supervising, the kennel should be a good and comfortable place for them to go.
You might also want to consider depending on where you live and how it's laid out, maybe some baby gates that will prevent them from going to various areas of the house. Those are probably the most basic common sense things I would think that you would need to do first.

It's similar to baby-proofing your house. Anything they can get into or chew on, you need to get that out of harm's way—shoes, dirty laundry, anything like that, that they could inadvertently chew on and destroy or ingest—the same thing with chemicals or toxins that they can get into. You also want to get a trash can that they can't flip the lid up on. If you have cabinets that are pretty easy to open or push open, you’ll want to get child locks on those. Anything that you can think of that a child could get into that could be harmful; then you’ll also need to puppy-proof that.