"So how did Brunner do it? To start with, he spent nearly three years reading up on topics from the role of genetic inheritance in disease to links between population spurts and urban violence. He also spent a month in the US in 1966, visiting Los Angeles, San Francisco, Chicago and New York. Then, breaking with his usual work routine, instead of outlining his plot, he filled 60 pages with thoughts before hammering out a first draft.
As he went, he devised a series of ‘parallel thought exercises’ to generate ideas."
This process makes me think of the 'premortem' concept in behavioral economics. In brief, it's the act of thinking/assuming that some event failed in the future - and then writing history leading up to that event. If interested, Richard Thaler writes a useful description of this: https://www.edge.org/response-detail/27174.