It is important to make expectations clear from the beginning. What time do you expect them to contribute? How do you expect them to communicate? What support are you offering them? What support are you not offering them?
For many research projects, it is not possible to exactly define the actual outcomes, but the amount of time that students work and the structure of the deliverables can be made clear. To help students devote the required time to their research, it can be helpful to agree on designated work times and even a workplace. Students can be asked to keep a detailed work journal, in addition to writing work plans and progress updates. Be clear about what students should prepare in advance of regular one-on-one or group meetings. This is particularly true when students are contributing during the academic year, when they may have many other responsibilities demanding their time.
It is important to agree in advance on the timing and scope of deliverables such as written reports and oral presentations. For example, in a 10-week summer research experience, students might be asked to give two 30-minute presentations (an initial research plan and background talk, followed by a final talk) and write an initial research proposal and a final paper in the format of a conference paper. Or perhaps if their contributions were to a project with established goals, you might agree to work towards some subgoal of the longer term project.
It’s also important to set expectations for any other researchers who might be working with the student, communicating how much time the student has committed, what reasonable progress might look like, and how to support the student in their learning.