This article argues that a public affairs plan is essential for any organisation to prevail in their competitive struggles for policy influence. We propose a seven‐step approach to devising a public affairs plan based on scientific findings and practical experience. The article maintains that any public affairs plan should be rooted in scientific, evidence‐based and practical insights. The different components of the plan—situation analysis, goals, alliances, audiences, messages, channels and impact measurement—should all be attuned to one another and to the context of the policy file. Each SMART objective should serve as a red thread throughout the different components of the plan. The plan should be realistic in terms of goals, time and costs. It should be flexible enough to withstand exogenous shocks and crises. Those who fail to start with a written plan will bounce around and be driven by the moment. An evidence‐based public affairs plan, in contrast, provides purpose and direction and will increase the chances of securing policy success.