Ask for something huge first, and the small ask lands easier

Researchers asked students to volunteer as counsellors for juvenile delinquents two hours a week for two years — almost everyone refused. But when that huge ask was followed by a far smaller one, a single two-hour zoo trip, compliance nearly tripled versus asking the small favour cold. Rejecting the first request creates an obligation to concede on the second.

— Robert B. Cialdini et al., Reciprocal Concessions Procedure for Inducing Compliance: The Door-in-the-Face Technique — Journal of Personality and Social Psychology, 1975