• Summarise what you want to say in no more than three bullet points. Policy workers’ lives are fast-paced and they do not have time to sift through long texts.
• Use common language and explain yourself clearly. Your science needs to be explained without confusion, yet you must not talk down to policy workers or come across as patronising.
• Practise communicating your science with people from outside your field. Valérie Masson-Delmotte (IPCC Working Group 1 Head) suggests to practice with teenagers as she says “You have to keep in mind that policy workers are not scientists. Many of them do not have a science background... When you do practise with teenagers, when they don’t understand you, you get very quick feedback”.
• If you include graphics make sure they are simple and clear: use a maximum of three colours (advice from Panos Panagos, Research Scientist at the Joint Research Centre).
• Remember timing is important. Science is only useful to policy workers when it is relevant. If you approach a scientist weeks or months after an event they will not be interested.
• Try hard to be unbiased in communicating your science.
• Do not advocate what should be done after you have provided scientific evidence. That is the role of the policy worker. A scientist’s role is to supply the current state of affairs for a particular topic. If you start to advocate a specific pathway you can appear biased, which may lead to your research becoming distrusted.
• If you are clear and concise when explaining science to policy workers, then they will know you are a useful resource to contact, and so may ask for your assistance again in the future.

Source: https://www.egu.eu/policy/basics/science-communication/