What are your biggest regrets/mistakes when buying your home?

My husband and I are looking to buy our very first house in the next few months! We're so excited to have something of our own, although, part of me is worried as I know there is so many things that can go wrong! I would love to hear some input from those of you who have already gone through it. What were your biggest regrets/mistakes when buying your home? What would you do differently? Thank you!