For Tamilians, Diwali is a morning affair. On the main day called 'Narakachaturdasi' - everyone in the family take an oil bath before sunrise. Hence they usually wake up really early (Something like 4.30 AM) in the morning for an oil bath (or a shampoo in the recent times).. The elders usually place few drops of oil on the family member's head before a shower.
A platter is then decorated with the family's new clothes, some boxes of fireworks, sweets, warm oil (usually gingilly oil or til oil), coconuts, bananas, betel leaves, betel nuts, flowers and milk.
For those hailing from Tanjore, the custom is to first take a small quantity of 'deepavali lehiyam' (medicinal, ayurvedic paste) after the oil bath and then have breakfast. Drawing a huge rangoli and lighting diyas is an important part of the tradition as well, just like it is elsewhere in India.
After the family is ready and dressed up in their new clothes, the puja begins. After the naivedhyam (offering to the Gods), youngsters touch the elders' feet for blessings. Family members head out to burst firecrackers, enjoy the sweets and start their day on a happy note. As the day progresses, temple visits are made, gifts are exchanged and sweets are distributed to family and friends.
That's Diwali - The tamilian way! :-)