Preflight
Every flight starts on the ground. Check props for chips and cracks, spin each motor by hand feeling for grinding or play, confirm frame screws are tight, inspect wiring for chafe, and check the battery for puffing or damage. Confirm control response, flight mode, and failsafe behavior before the props are anywhere near your hands.
Write go/no-go criteria in advance: maximum wind, minimum visibility, minimum battery, required clear area. Deciding on the ground, in advance, is how you avoid a bad call under pressure.
Reading problems
Jello in video, oscillation, and unstable altitude hold usually mean vibration: balance or replace props, check bearings, check soft mounts. Circling in position hold ('toilet bowling') points at compass calibration or magnetic interference. Drift with centered sticks in a self-leveling mode points at level calibration, trim, or a damaged prop.
A motor too hot to hold after a short flight means excess load, damaged bearings, or a prop and motor mismatch. Warm is normal; hot is a warning.
After a crash
Never relaunch immediately. Inspect the frame for cracks, check motor shafts for bend, replace suspect props, and look for pinched or cut wires. Bench test with props off, then do a low, short hover in an open area before trusting the aircraft with distance or altitude.
Aim for a hover at roughly half throttle or less. That margin is what lets you correct for wind and recover from mistakes.
Records and readiness
Airworthiness is a property of specific components, not of an aircraft in the abstract. Log component installs, serial numbers, flight hours, faults, and the corrective action taken. Export and save a known-good configuration whenever the aircraft flies well.
This is the entire idea behind a maintenance tracking system: instead of guessing whether an aircraft is ready, you can see what is installed, how long it has flown, and what is outstanding.