Your Own Bedroom
On one hand, new parenthood means you're about to learn just how little sleep your body can function on. On the other, you'll be hitting the sheets whenever naps and newborn sleep permit. Make sure that your bedroom feels like the comfortable, relaxing sanctuary it should be.
If you don't already have a good nightstand, now's the time to get one, and make sure that it has room for a phone charger, reading materials, a clock, and a lamp. Go through your drawers to ensure that you're well-stocked in the postnatal wardrobe department, with everything from nursing bras to comfy clothes that you feel good in. If you're feeling especially indulgent, a minifridge (like the kind you had in your college dorm) would be a total luxury for keeping bottles of breastmilk, formula, and just regular old water cold and easily accessible.