As soon as a new batch of work starts, begin writing the update that will be sent to the client at the end of the sprint. Even if it won’t be sent for 2 weeks. This forces the team to keep the important things in focus the whole way through, and not to rush them in the final day.
Write the update somewhere that everyone can see it (usually in the description of an asana task). Treat it as a “live document”.
Always try to include either or both:
A live demo environment, with detailed instructions (”Go here, use these credentials, click this button etc. etc.”).
A short video (can be recorded with Screen Studio). It’s fine to re-record this - you might record one at the end of the first week, realize important things while recording, not send it, and then record a new one the following week.