This is what I've started doing.
My newsletter is my pillar content.
Then I create content based around that.
I schedule everything for Twitter usually and cross-post to LinkedIn with some different copy.
One important thing is to make sure you don't spread yourself too thin.
Focus on one platform, cross-post to others.
Then only when you feel you have enough "brain space" as I call it, you can pick another platform to build on.
You can find me on LinkedIn too linkedin.com/in/willhelliwell