Since I am so old I need to go back 30+ years and here is what I wish I had known.
I wish I had known that all kids are the same. They all go through the same frustrating stages, they all become snotty and self absorbed teenagers and they all (for the most part) become wonderful, well functioning adults.
This would not have changed how I raised them or disciplined them. This is our job as parents to guide them through all these yicky times. But, what I would have changed, is I would have worried less and enjoyed the unyicky times much more. I would not have lost sleep thinking that my kids were worse than my friend's kids, or that I was too strict or not strict enough, too impatient or too quick to give in. I would realize that God provides parents with the instincts to raise their children and then to let them go.
True, some of my children floundered more than others. Some had to fight with the genetics they were given and learn that they had an addictive personality and that they can't just wish that away or pretend it is not a fact of life for them. Sometimes, this is a lesson that is never learned but that is not necessarily a reflection on the parenting they received but on the hand they were dealt and played incorrectly.
The time passes so quickly and before you know it they are grown and gone, living their own lives and making their own decisions. This is why I believe grandparents are so much more effective than parents. We have been there. We know that this too shall pass and we can relax and enjoy our time with them.
My Amy (on the right) and my niece, Steph with their Grandpa.
My Chuck with his Grandpa.