First hip throw post. Harai Goshi translated is sweeping hip throw.
So I set up the throw usually by loading up my limbs in the opposite direction of their throw. Base foot goes back, sweeping foot foward, leading arm up and bent and my throwing arm down and straight, and i use my torso to hip into my opponent.
Then with my base leg i dig into the ground while my sweeping foot swings back to clip my opponents legs or hip.
Using my abs and lumber i arc towards the ground to which provides more leverage for the throw and finally my arms will wheel throw my opponent over my body.
Only when my opponent's hips are clearly above my own i will rotate-chest to add the final rotational force. Otherwise i will lose my footing if i do this too early.
I find hip throws, especially harai goshi and uchi mata, to be such a beautiful technique because every limb on my body is working together by moving separately.
The combination of these different forces produce a single momentum that is very powerful.