To have good foundation is to practice the Ngondro
So, it is very important to build a good foundation for the practice of this Great Secret, the Great Perfection, Great Wisdom. And to have this good foundation one is to practice the Ngondro and to accomplish the 500,000 Preliminary practices like 100,000 prostrations, 100,000 mandala offering, 100.000 recitations of 100 syllables, and bodhicitta and refuge prayers.