There really are no beginnings.
I have read many books on writing and they all say to start at the beginning. The beginning of what? Thoughts happened to get you to the beginning. All is already known. Time does not stop for something to begin. What is really new?
Each action of a story - or life - grows from the one before it. That action evolved from previous actions and will influence further actions. Each much be connected. Each must be sensible and pleasing, like a lullaby. The reader should not be allowed to pause to question an action; the pause must be to understand the motivation behind it.
Pivotal points are the intersections, the choices of the character. Does he affect the change or does the change affect him? Does he interrupt its course of action or does it interrupt him? Choose the one that would have the most emotional impact on the reader. Choose the opposite of good. Venture into the dark side. Controversy is passion.
If you had taken a left instead of a right, had skipped that last drink instead of staying for one more, had chosen to go to the dance with that one person in high school who asked you instead of staying home and pining over the one that didn’t, there would have been a different change. Your life as you know it now would not be as it is.