What do new parents most need to know about caring for a newborn in the first three months?

We are first-time parents and our baby has just arrived. The first three months feel overwhelming and we are not sure what to prioritise. What are the most essential things new parents need to understand about a newborn's development, feeding, sleeping, and crying during this period? What is considered normal and what signs should prompt us to contact a health professional? Any practical guidance that helps parents feel more confident and prepared during this critical early stage would be very helpful.