I think I've posted things from Jane Friedman here before. But in case anyone's New Year's Resolution involved getting the damn book off your computer and onto someone else's, here's her list of self-publishing tasks. Light on the promo side, as she acknowledges... https://janefriedman.com/self-publishing-checklist/
It's useful to see someone else's workflow. It would be interesting also to see a more complete list, including the activities she undertakes to market as well as prepare her book.
Just stay away from all marketing plans when it comes to self publishing. It's NEVER worth it. You spend so much and get so little. Just do the leg work yourself.