Elevons have little to no slop

motor turns freely

Propellers installed correct direction

Propeller spinner is tight

Center of Gravity (CG) in correct location

Battery stays secure during a brief jostling 

Confirm CG 

Motor Direction

Pitch up (right stick down, Elevons up)

Pitch down 

Roll right (right stick right, Right elevon up & Left Elevon Down)

Roll left

Throttle up (thrust in correct direction)