I was a solo consultant from 2005-2007 and supported my family of four during that time.
I suggest working to become recognized for your expertise before you go solo.
I prepared by blogging, writing many articles and two books, presenting at conferences, and teaching classes. Additionally I was a consultant for a security company for several years, which meant I had a lot of contacts who might hire me for work as an independent. When I was considering going solo, I emailed many of them to let them know I was considering an independent path.
I decided to make the leap when a prospect said they had months of work for me to do. I left my job, but that prospect was all talk! Fortunately I found plenty of other work to compensate.
I paid my bills by scheduling and teaching independent classes. Above that I consulted, which was "bonus" at that point.
I read this book back then. It's from 2000 but the overall message is still relevant:
https://www.amazon.com/Serf-Surfer-Becoming-Network-Consultant/dp/0782126618
Be sure you take care of the "infrastructure" issues early -- taxes, business bank accounts and credit cards, insurance if you need it, etc.
Finally, it's best to decide right away if you intend to be a solo consultant, or if you are starting a business that would employ others. The latter is more complicated, obviously.
It's extremely hard work and the pressure is enormous. Two years was plenty for me but I'm glad I did it. Good luck!