After the rice is served some water is taken in the right palm and letting it leak through fingers the plate is circumambulated clockwise and the rice is sprinkles with the remnant. Doing what is called paricheshanam is kula acara -not applicable universally. In this case the water for the three circumambulations (pradakshina in samskrit) must be taken separately. Another person should pour a little water in your hand and you partake it. Taking little rice - mixed with ghee, if you are used to taking ghee with food- without touching the teeth the rice is swallowed five times one each for each prana. This is what is called prana agnihotram. Again a little water poured by another person is partaken. At last, is one free after this to eat the rest of the food? Just a minute, a little food is placed on the ground to the right side as bali for yama, chitragupta, and prethas. (chitra bali). This is done if vaishvadevam is not been practiced.
Ok, now you can eat, (at last!) but there are some do's and dont's. (I knew it!)
Food should not scattered on the ground around the plate. One should not comment on the food. 'Annam na nindhyath' says the upanishad. One should not talk while eating. If one does so his lifetime will be shortened. An exception has been made for the gruhasta who sits with others to eat. He has to see other's plates and give suitable instructions to the wife.
One should take just what his mouth will hold. Once food is put in the mouth it should not come back to the plate. Therefore one should not take something take a bite off it and return it to the plate. Sound should not be made while drinking or eating. While a group of persons are eating together one should not get up and leave. If anyone does so, all should leave says the sastras. If there is a compulsion to leave one can split the row with a little water and then leave.
Most of these are followed as etiquette.