Here is my input too, based on (sometimes bitter...) knowledge gathered from other pilots:
- make sure the battery is well seated in its compartment, by checking it clicked on both upper & lower clipses (P3)
- check the altitude for RTH if AC losts RC signal (make sure the flight over a straight line to home will be well above any buildings or trees etc.)
- video cache is ON (for cases when the bird will get lost, so the video from the phone/tablet will help somehow finding it)
- for older batteries, check the actual capacity after charging (Remaining Pwr), not the Total Capacity
- check the compass mod value, its normal value should be in the range 1400-1600
- check sensors (gyroscope, accelerometer)
- at travel altitude go for a while in ATTI mode, to see wind direction, hence understanding any possible flight-to-home difficulties against the wind
- check locked sats (at least 9 pcs)
- make sure the Home point is locked on the map
ANY further input is warmly welcomed !