time your flights!

Even if you have telemetry and/or OSD, timing your flights remains an essential tool to minimise unnecessary crashing due to low battery.
To find the right flight time for your setup and your flying style, its a good practice to fly for 2 minutes, then disconnect the battery and let it rest for a minute. Now measure the voltage. You should get around 3.7V.
If you read less voltage after a minute, reduce your flight time next time by 10-20 seconds.
If you read more than 3.7V after a minute of rest, you can add a few seconds to your next flight.
If you can read the live voltage under load either over telemetry or OSD, you should land soon after the voltage has reached 3.2V for the first time during medium/high throttle.