Things have changed during two decades or so.
So, to help you avoid many mistakes, here are my new observations:
1. Don't post pictures of your new grandchild without permission from the parents, even if you took those pictures.
2. Don't start showing off pictures of your grandchild at a party; unless, someone asks.
3. Don't tell the new parents what was the 'right" thing to do in your days. Medical science has grown faster than you know.
4. Accept what the parents are doing as they are the ones who are responsible for that child even after you've left this earth.
5. Don't buy stuff for the child without consulting with the parents. Even toys.