Depending on their personal preferences, some of the participants will prefer to know the agenda in advance and will feel the need to prepare (at least mentally). Therefore, send them all a short email a few days before the workshop that: 

1. States the purpose and goal
2.  
3. Summarises the briefing call in a nutshell for the participants to feel heard 
4.  
5. Shares a “big-picture” agenda (don’t overwhelm them with details)
6.  
7. States clearly if you expect the participants to prepare something beforehand. 

In some cases, it may be useful to define some rules for the workshop. Maybe you want to request a screen-free space or expect attendance for the full duration to avoid participants to come.

In preparation for a full-day workshop, I was inspired by Pam Hamilton and like to invite participants to do a small preparatory task. This will mentally prepare them for the session and collect ideas or information in advance.

Instead of a pre-reading that participants often skip due to conflicting priorities, a prep-task asks participants to reflect on the workshop in a creative and active way. It can be as short as a few minutes, asking them to think of a story or bring a picture that is related to the workshop objective.

If you decide to ask for a prep-task, make sure that participants get time to share their results. You can effectively do this during the warm-up exercise.