All of it is true.
It can be hard, as a writer, to keep that in mind–you have the whole story to keep in your mind–so polishing (or demolishing and rewriting) your opening is something best done at the editing stage. Once your whole story is down on paper, go back to that beginning (after taking a break from the manuscript so you’re looking at it with fresh eyes) and ask yourself–if I were a reader, would I pick up this book based on this first page?
I’m not going to rehash the advice in the articles I linked to–go read them for yourself. Instead, here is the beginning of one of my favorite books of all time. I’ll post it, then we can discuss why it’s so great. I think I’ll make this a regular thing.