Kali Puja fasting is mainly observed during Diwali Amavasya Kali Puja. It can also be observed during any Amavasya day (no moon day in Hindu calendar). The only rule is that Amavasya tithi should be present during midnight – for this reason Kali Puja fasting can be the day before actual Amavasya tithi.
Goddess Kali fasting is from sunrise to next day morning
sunrise. If you want you can also starting from the starting of Amavasya tithi to
the end of Amavasya tithi if you know the exact tithi time where you are located.
On the day of Kali Puja, fast and offer anjali (devotional
offering/salutation). When breaking the fast, eat fruit first. And on the next
day, do not eat any non-vegetarian food at all.
Worship the Goddess with red choli (sari/cloth), sindur
(vermillion), and red hibiscus flowers, which are dear to Goddess Kali.