When writing marketing materials, people always talk about tone of voice. This can be quite a vague phrase, but what is usually meant by it is the type of language that is used to really speak to the people who read it. Should you use formal language, for example? Or might it be more appropriate to write informally to people? It will depend on the results you want to achieve and the topic you are writing about.
You can conduct plenty of market research, seeing how other businesses write. Use this to either stay on brand, or to deviate and draw attention to yourself for standing out.
Talk to people who could be potential customers. If you can hold focus groups, that’s very helpful. Find out what appeals to these people and the kinds of marketing they might react to, so you can understand them and write materials that they would read.