The trouble with advice is, well, everything. You can't hear it or understand it right when you need to, and some stuff you just have to learn for yourself. But because I can't keep my mouth shut about all the wisdom I've obtained--mostly the hard way--over the past few years, here are my must-have tips to bringing a new life into the world:

Just take the bathroom doors off their hinges. There's no such thing as privacy anymore. The only time you get to pee on your own now is at work, if you are lucky enough to get to go there occasionally.
Get a swing. Just trust me on this. Not a cool one, or a special kangaroos in their pouches make this soothing movement one--get one that swings as much as possible and as fast as possible (within reason for a newborn). It is okay to let your baby sleep there. Maybe even all the time.
All the other moms will do cool Pinterest-y things for every milestone you didn't even know existed. Do not be made to feel small by this. I once walked all the way around a mall with baby vomit on my chest without knowing it. Motherhood is a warzone more than it is Martha Stewart, and you can write things ABOVE the pictures when you post them on social media, so you don't need to fret about having a chalkboard or a specially made onesie for every occasion. Survival is key, that is all.
If you are one of these Pinterest-y moms, wow. Good on you. You should consider using this talent to achieve world peace, because it is nothing short of incredible. You should also consider using some of that time to take care of yourself so you don't burn out, just sayin'.
One of your boobs will now forever be bigger than the other one. Just learn to love it and buy good bras.
You might have an additional stomach now for each child you have. I'm not saying it will definitely happen to you, I'm just saying it definitely happened to me.
Do not stress over the milestones. I had one kid walk at eleven months, and another at about nineteen months. They both run and jump now. It's all going to be fine--and if it isn't, there are a lot of people who've been through it and a lot of people who can help.
ASK FOR HELP. Honestly, people love babies and they love you. Ask.
Do not change diapers in the dark. You will regret it. One day.
They make disposable washcloths with lavender baby soap in them--for when you ignore #9 and you end up needing to bathe your baby in the sink like a teacup because the bathtub just takes too long and g*&&&^%&^*t, you are exhausted.
Shoes don't stay on babies. I'm just warning you.
Buy like three bottles of baby Tylenol and two hundred pacifiers and keep them everywhere. Just...trust me.