I just try to reduce the risk... fully-charged iphone, no apps open.
Phone to Airplane-mode.
I turn the Anafi on so it gets GPS.
I open the controller
I open the FF6 before connecting the USB to the controller.
1 in 10 times the video is black, so I remove the USB and re-plug in.
I have found (purely for me) that the connectivity works better if I open FF6 manually first, rather than plugging in the iphone and getting "do you allow freeflight to open".
I had the video freeze just after take-off on Saturday and I needed to restart the FF6 app but the Anafi just hovered and waited for me. I could still control the Anafi.
I'm still a newbie with this machine but I try to be consistent in my connection routine - just like doing a basic site check around you before take-off (trees, powerlines, people, dogs... Wifi/network ok, battery power check once hovering for 10 seconds - while it sets the takeoff GPS position.)
Check-lists are worth it. You should never be in such a hurry that you haven't done your checks!