From this, most of the rest follows!
A suitable research project will complement the rest of your lab’s work, but will be distinct and easily identified as the student’s own area. There will ideally be some scope for the student to “do their own thing” in developing the project. Remember that the student is not here to work as a technician, but that they will need heavy supervision in practical aspects, especially in the first year. Make sure the project has sufficient flexibility to allow completion in three years.