[Holi is celebrated on the last full moon in the lunar month of Phalgun, which fell on March 1 this year. The festival celebrates the Advent of Spring, though given the nature of seasons in India, it is often the only day of Spring.]
You can use dry dry herbal colours that wash off easily. Or use a paste of almost indelible aluminum paint.
You can buy your colours from a store. Or soak flowers overnight to extract your own colours.
You can smear colours on a person’s face before giving them a hug. Or throw balloons with coloured water from behind.
You can play with your friends, and use the festival to make new ones. Or play dirty and get your revenge on enemies.