What has been your biggest mistake?

ive made far too many to nail it down to one. I have done a lot of bad messed up shit when i was younger and i regret some of it, mostly the stuff I never got away with and paid for one way or another but I think the thing i regret the most is stupid little things i did when my son was first born.
I was utterly clueless on how to be a parent and the new born baby stage is really rough even when prepared and i feel i made some mistakes, nothing major but its still things i wish i did different