This is a tough question, too. For me, I don't tend to start with the plot, I start with the character I want to write about, the story about them I want to tell, and the world that they would need to live in to make that story possible. The plot comes out of that. You just have to tell the story that you want to tell, that's important to you, that's your own take on it and nobody else's.
When you start developing your character, you have to figure out what his or her conflict is, what problem she's facing that's at the core of her story. The place she needs to go, the place she needs to get out of, the thing she needs to get, the mystery she needs to solve.
Also, if there's a type of story you really like (whether it's epic quest fantasy, cozy mysteries, sf adventure, whatever) you can look at it and ask yourself, what elements are missing from these stories that you really want to see. (For a couple of broad examples: A cozy country house murder mystery, but instead of a high society detective, the cook and a gardener team up to solve it. Or a fantasy quest, but instead of being alone the adventurer is a single parent with kids to take care of.) Or look at the types of stories that you always liked, but that aren't being told very much anymore. Remix, combine, put your stamp on it by putting in the stuff you always wanted to see.
Still taking writing or publishing questions here.