Don't look to me to tell you what you should do; the hottest vocations of my generation will likely not even exist for yours (example: petroleum engineer). Look externally, experiment, measure, iterate. (essentially your first point)
* Make lots of mistakes, because mistakes mean you're trying new things, but with 2 caveats:
1/ try not to make any fatal mistakes
2/ don't repeat the same mistakes
* You have the resources of multiple generations of lucky & hard-working people at your disposal; don't waste them but make sure you use them (meaning educated families, diverse experiences and money)
* Your overall goal is to do your best to leave the environment you were born into better-off than it was when you started, meaning you've worked to improve the position of your family, community and the broader world.
This is all well and good when they're in school and still dependent on your financial support. Once they're on their own (say, at age 22), and start making mistakes, the stakes are a lot higher and the margin for error a low narrower.
Let's say you majored in something but did poorly overall. That's mistake #1. You won't have as wide of a berth for mistake #2, because you are likely still suffering the consequences of #1.
Pick something and try to get really good at it. If that doesn't work, pick something else.
(Privileged, top 5%-er) parenting in 2019 is a constant battle against the temptations of over-scheduling and over-enrichment. Kids need time to relax and goof around without being under pressure.