I think the single most useful thing to keep in mind is to not to let yourself get overwhelmed, take care of the important stuff first, worry about the smaller stuff later. When the world falls apart, and it will, the welfare of children comes first, anything else can wait.
Don't pay too much attention to what other people tell you, all kids are different and you're going to have to find your own groove. That's not to say you can't take on advice, just that not every bit of advice you get will help you. There's nothing wrong with asking your parents, grandparents or friends for advice, just don't expect that their solutions will work for you as it did for them.
Whatever you do, prepare for the worst, not because it will happen, but because it will if you aren't prepared. It's better to be late and over prepared than having to deal with a crisis unprepared.
Have some fun with your kids, they're not young forever and they grow very quickly, play with them and have fun. Maintain parental boundaries though, I think this is the most difficult thing to balance. Think of it like you're a workplace foreman, it's important to have good relationships with your charges, but it must be clear that you're in charge, you are responsible for them.
Kids are gross, get used to it quickly because it only gets worse. Spew and poo are the least of your worries, children will constantly find new ways to disgust you.
Don't worry about what other people think, they are not you and they are not responsible for your children, let their judgement roll off your back, their opinions aren't important and it's a stress you don't need, your children will supply you with all the stress you can handle, don't willingly take on more.