Establish a reference
Record the receiver, sample rate, gain, frequency correction and time source. Without a stable baseline, screenshots are difficult to compare and anomalies are easy to misread.
Read the waterfall in context
A trace shows energy, not intent. Compare bandwidth, duration, repetition and neighboring signals before assigning a likely mode or source.
Make observations reproducible
Save short captures when permitted, note UTC time and keep calibration checks near the observation. Respect spectrum rules and the operating terms for the equipment and service.