First, think outside the box. Then associate your thoughts with things you have observed or experienced. This is the essence of creativity. Always be filling your “card catalog” with experiences and knowledge. Then take those cards and put them together in different combinations.

Ed Sheeran and Neil Gaiman are in the top 0.000001% of their fields. They're among, say, 25 people in the world who repeatedly generate blockbusters.

If two world-class creators share the exact same creative process, I get curious. Also, while writing this, I found a video of John Mayer doing the same thing.

I call their approach the Creativity

Another idea if you want to push against the mental pressure that kills good ideas, from Paul Graham’s recent essay on how to do good work: “One way to do that is to ask what would be good ideas for someone else to explore. Then your subconscious won't shoot them down to protect you.” I don’t know of anyone using this technique, but it might work.