There is virtually no difference between writing well for the web and writing well for mobile text. The content should be short and precise, and the overarching guideline is to deliver the same information but in less space.
On a mobile screen, it quickly becomes apparent how the task is accomplished. Once you have a responsive design template on your pages, you should review your content on your mobile phone. How does it work for you? As a web editor, you are the one who can adjust the user experience.
We tend to write overly long texts for the web, wanting to deliver a lot of information. The best advice is to try to adopt a user perspective and assess what information the user needs to receive. It can also be a good idea to test pages with your users. How do the pages work for those who need to receive your information?
Here are some general recommendations for reviewing and editing web texts. Of course, texts vary greatly. Whether it's a text about a social event on a Friday afternoon or a research-oriented article, it’s important to remember that the text is for the web, not for an e-book reader or the printed version of a journal.
People are interesting to people. Therefore, the text should address the reader directly (e.g., using "you" or "your"), if relevant. Using quotes or stories from others can make it more relevant.
Overall, users should not have to stop, be unsure about the message of the text, question the page's relevance, or be left with too many unanswered questions. Clarity and accessibility are key.