asks: How do you avoid using deus ex machina excessively in your books?

In writing, "deus ex machina" refers to when all the crazy problems in the story are magically solved by the arrival of some new character or sudden event. For example, maybe the main character is about to lose her home, and she needs surgery too, and her brother is about to be shipped off to foster care. The situation seems hopeless. Then suddenly, a rich uncle--who has never been mentioned before--shows up and saves the day.

The reason this is undesirable is because it feels unrealistic and contrived. Maybe even accidental. Readers want characters who actively do things to fix problems, not have things happen to them constantly.

To avoid this, remove the suddenness of the solution by building up to it. Mention the uncle earlier in the story so readers are aware one exists. He doesn't have to show up earlier in the story, but he has to at least be talked about. Add some elements to the story so it doesn't seem so mystical that he conveniently shows up. Like maybe the main character talked to him on the phone. By making the arrival of the solution less sudden, it'll feel more natural.

If you're a pantser like me (I find it hard to plan my stories, so I write by the seat of my pants) then sometimes the solution isn't apparent until you're nearly there. If I never edited my stories, I would have the deus ex machina problem all the time. Fortunately, we can always go back and edit the story to add in elements that lead up to the solution. Make it feel like a progression, rather than a miracle.