Putting in the work.
There’s no way around it. Sometimes I have gotten lucky in the creative process and a great idea pops into my head, execution is easy and the client approves quickly. But more often than not, it’s hard work. This is a good time to test out the ideas, see if they hold up under scrutiny.
There is an exception to every rule, of course, but this is, so far, in 25+ years of my career, the only thing even remotely resembling a “formula” that I’ve ever found in the creative business. So I often tell young designers, “You better have some back bone!”