The best way to start all sessions, after the greeting, is to clarify what students want to work on and to set goals up front. If they've uploaded a problem, ask them if there is a particular part of the problem they are struggling with, or if they want to go through the whole thing. Then find out what they know: ask them where they think they should begin or if they have been doing similar problems in school. They may know how to get going and just need help with a later stage of the problem. In this case, students will get frustrated if their tutor insists on walking through every step that they are already comfortable with. Letting the student be the guide and solve the problem until they get stuck will both keep them engaged and invested AND give you a chance to identify the gaps and figure out where to best focus your time. Some students come in with work already done on another piece of paper. If they tell you they've already started, you can ask them to take a picture of what they've done so far. The more you get from your students up front, the more efficient and effective you can be in the session.