Start with spend and results
Look first at how much was spent and how many customers or real enquiries came from it. Clicks and impressions only matter if they lead somewhere.
Compare like with like
Compare this month with the same month last year, or with the previous few weeks, not with a single unusually good day. Seasonal businesses especially need the longer view.
Ask what changed
Every report should say what was changed since the last one and why. If nothing changed, results usually drift, and that is worth knowing too.
Watch the cost per result
Divide what was spent by the results it produced. If that cost is creeping up week after week, an ad has worn out or an audience has been used up, and something needs refreshing.
Expect a plan, not just numbers
The last part of any report should say what happens next: what will be tested, paused or expanded. Numbers without a plan are a record, not a report.