Operational planning and emergency procedures
Planning before the prop turns
A defensible plan covers: task and airspace check (including NOTAMs), weather and light, site survey on foot with a ground risk assessment, identification of people, animals, traffic, powerlines and radio interference, permissions and notifications, crew roles and briefing, battery and payload plan, geofence and failsafe settings, abort criteria, and the emergency plan. Document it. The job is not to produce paperwork; it is to make the right decision available under pressure.
Emergencies you must rehearse
Lost link: the aircraft performs its configured failsafe, typically climbing to the set return-to-home altitude and returning. Set that altitude above the tallest obstacle with a margin - a failsafe that flies into a crane is worse than none. Fly-away: do not chase it; note the last position and time, warn people, notify appropriately. Battery critical: land now, do not stretch a leg. GPS loss or compass error: expect degraded stability, reduce to a safe attitude and land. Fire, injury or aircraft conflict: protect people first, then property, then the aircraft; give way and descend if manned traffic appears.
Worked example / rule of thumb
Before every flight ask: if control is lost right now, where does it go and who is underneath? If the answer is unacceptable, you are too close, too low or too far.
Traps
Setting RTH altitude below obstacles; chasing a departing aircraft; forgetting to brief bystanders and observers; no plan for a member of the public walking into the operating area.