The best automation flows are the ones customers don't notice as automation at all. They feel like a fast, competent version of a conversation with your best rep.
Start with the outcome, not the mechanics. Before building a single step, define what a "won" conversation looks like.
Keep branching shallow. Flows that ask five questions before providing any value lose people.
Finally, always build an exit ramp — a clear "talk to a person" option, available at every step.