Re: Tenchi nage
Lead them away from where they are strong: take their centre.
Tenchi nage was explained to me first as two parts: 1/2 sumi otoshi (corner drop) 1/2 irimi nage (fingers past eyes).
Heaven AND Earth, not Heaven OR Earth.
Also, remember to "stand in between Heaven and Earth" (back straight) when you do it (remaining strong in posture and mind).