That is usually because the quad is not sitting level and so it tries really hard to make it level.
Make sure that Stabilization->ZeroTheIntegral is ENABLED.
Take off immediately after starting the motors.
(after initial testing to make sure that it doesn't flip instantly) Do not take off slowly. Jump up into the air about knee high.
Do not "help it" with transmitter sticks during takeoff. Leave them centered until after you are in the air.
Do not take off from the side of a hill. Take off from flat ground, Preferably over thick grass in case you must chop the throttle and let it fall from knee high.
There are other things that can cause it, but if you know your settings are 1112-1116 or so for all motors, and so your motor neutrals are set to say 1116 to 1130 or so, then it is more likely to be set up correctly.