Great advice. Two aspects of this situation which haven’t been touched on: (1)how to deal with being impugned by your previous employer; (2) how to let people know your new situation.
When you aren’t around to defend yourself you might be blamed for everything that goes wrong. When I left one job, partially over my opposition to pursuing a major contract, the company went ahead with the contract. About a year later the contract blew up with a loss of about $800,000, much as I predicted. A few months after that, one of my friends “inside” told me that the company was saying that I had been in FAVOR of the contract. Implication: I’d been canned and good riddance, instead of, I’d left and coulda saved them a bundle if they’d listened. Damage to reputation: I don’t really know, but I bet I didn’t get a few calls as a result.
Also, your old employer isn’t going to tell anyone that you are in business.
So, if you have valuable contacts from that job, make sure you stay in touch. You can tell them you aren’t soliciting THEIR business because you know that they are happy with XYZ Firm, but you are open for OTHER business, and if they know of someone else who might use your services, please let them know…