New to PP

I know it’s been discussed a lot here but looking for fresh ideas instead of filtering posts. I’m new to private practice. I am setting up my PLLC and debating on joining headway while I get it up and running but I know that comes with its pros and cons (leaning towards not doing this and just being patient with my own). I’m currently licensed in NY, CT and CO.

What are people’s experience with

a) getting credentialed on their own with insurance companies using your own tax ID and what not

b) marketing? That’s my biggest concern right now is how to switch from a CMH to my own practice without a steady income and not guaranteed high caseload.