There are some basic aspects of Vesak Day that I really admire such as bringing happiness to others, especially children, the elderly, and handicapped. Worshippers plan a trip to the temple that day to buy incense, pray and offer flowers in worship. Traditionally animals have been let free on this holiday in a symbolic act of liberation. This is to signify the liberation of those in captivity against their will. Singapore had a government announcement to encourage people to let bugs go as a gesture instead of any other animals. Vesak is also a day where many Buddhists will eat a totally vegetarian diet.
I really like this description of how to celebrate Vesak Day and pay homage to Buddha from Wikipedia:
" Tradition ascribes to the Buddha himself instruction on how to pay him homage. Just before he died, he saw his faithful attendant Ananda, weeping. The Buddha advised him not to weep, but to understand the universal law that all compounded things (including even his own body) must disintegrate. He advised everyone not to cry over the disintegration of the physical body but to regard his teachings (The Dhamma) as their teacher from then on, because only the Dhamma truth is eternal and not subject to the law of change. He also stressed that the way to pay homage to him was not merely by offering flowers, incense, and lights, but by truly and sincerely striving to follow his teachings. This is how Buddhists are expected to celebrate Vesak: to use the opportunity to reiterate their determination to lead noble lives, to develop their minds, to practise loving-kindness and to bring peace and harmony to humanity."