pūrvakam

in a wrong way — Bg. 9.23

without following any rules and regulations — Bg. 16.17

in loving ecstasy — Bg. 10.10, Ādi 1.49, Madhya 24.173, Madhya 24.192

by chanting the Vedic hymns to perform the purificatory process — SB 10.8.10

preceded by offering of water — SB 8.20.16