The most important thing:

I've learned thatthis is the single most important word of all:

PATIENCE !!!

No mater how, no matter when, no matter what happened and even how hopeless the situation is.
Think of one piece of wisdom: everything will pass. It will change, it will move on.

The baby grows way too fast (might not look like it, but believe me, it does). Sleepless nights will occur. The baby will cry fro many reasons, even for no reason at all.
Just don’t take it on you, your wife or your baby. Remember. Things will pass. Take it as a lesson of tolerance you’ll need for later.

Your wife will also be as much on the edge as you (sometimes even more). Try not to take anything badly. It will pass. Later you can look back and you will see that most things were not really THAT important.