Every participant, camp leader and project partner have some expectations before the project. Clarifying the expectations in advance helps to prevent misunderstanding and conflicts during the workcamp.
Make sure that everyone knows what is expected of them during the camp, work-wise and in general. This can be done during the first few days by writing down all the work tasks and common expectations, e.g. coming up with common group guidelines or activities that people would like to do.
As a camp leader, you can ask the organisation, if you can talk to the project partner beforehand so that you have an idea of what is expected when you arrive. In some countries, this is a compulsory part of workcamp preparation. If this is not possible, you can discuss expectations with them when you arrive to make sure everything is in place. This can also help if project partners ask you to do tasks that are not related to the workcamp or ask you to do more work - if expectations are discussed at the beginning, you can always remind them of the ground rules.
Some additional information about the camp can be sent to participants by email/social media in advance, the information sheets are usually written many months before the camp and new information may come in, be sure to inform participants of any major changes a few days before.
When in doubt, you can always refer back to the rules and guidelines that were originally discussed.