Start here. This is the direct spoken answer to practice first.
Overview
Few-shot examples are useful when they teach a boundary the instruction alone does not communicate reliably.
Zero-shot prompting gives the task and constraints without examples. Few-shot prompting adds representative input-output examples. I start zero-shot when the task is simple and well specified, then add a small set of examples when they improve ambiguous classification, tone, edge-case handling, or output conventions in evaluation.