Following a child's progress should not feel like a second job. A few well-chosen checks do more than a daily inspection.
The first week: timetable and attendance
Look at the timetable together and note any day that is heavy. Then check that attendance is being recorded. A pattern of absence in week one is far easier to talk about than one found at the end of term.
Mid-term: the first results
A single mark says little. Look for direction across two or three: rising, flat or falling, and which subjects carry the change. Ask the child what they think happened before offering your own view.
The question that works best is not why is this low, but what would make next time easier?
End of term: the report and the invoice
Read the report for comments, not just grades, and settle fees early enough that nothing interrupts the next term. If anything on either looks wrong, the school office is the right first call.