Layering is the most effective way to dress a newborn, as they are still learning to regulate their body temperature. Cotton onesies and rompers are excellent basics that are breathable and gentle on skin; zip-up suits are particularly convenient for frequent nighttime diaper changes. For cooler weather, you can add a light sweater or use a sleep sack, which provides warmth without the safety risk of loose blankets. Mittens and beanies are generally not needed indoors, as babies release excess heat from their head and hands, and you can simply layer a sweater over a single top if temperatures drop.