While Hindu puja (prayer) rituals are more or less common to all the gods, several practices have evolved that are unique to Ganesha.
Ganesha can be worshipped even without an idol or picture. A bowl filled with rice, with a betel nut (or sometimes a coconut) placed on top represents him equally well. In many ceremonies, a priest will invoke his presence by creating a small cone of thick turmeric paste! Some devotees like sculpting their own idol out of clay for Ganesh Chaturthi.
Often, a devotee faced with a difficult, problematic or challenging situation in his life will make a vow to Ganesha, offering to break a certain number of coconuts at the temple if Ganesha will resolve his problems. The coconut represents the most evolved part of a human being – his head. Smashing a coconut before the Lord is symbolic of destroying one’s ego and surrendering oneself to His grace. When the ego disappears, the true Self reveals itself, much like the sweet water in the innermost recess of the hard shelled coconut.