Every night, before going to bed, do Vajrasattva practice, reciting one mala, a half mala, or at least twenty-one repetitions of the long mantra. If you can combine your recitation with prostrations, it will be very, very powerful; two powerful practices combined. You will collect extensive merit and purify unbelievably heavy negative karma. Otherwise, you can do your Vajrasattva recitation while seated. It depends on whether or not you have the opportunity to do prostrations and on how you feel. You can decide for yourself.
And if you can begin your evening Vajrasattva practice with prostrations to the Thirty-five Buddhas, going straight through and not necessarily repeating each buddha’s name over and over with each prostration as in the morning practice described above, that will also be very powerful because, as I have said, reciting each buddha’s name even once purifies many thousands of eons of negative karma. This practice is unbelievably powerful.