Mantra for Lord Ganesha is “Om gam Ganapataye namaha”

Meaning: I salute to or surrender to Lord Ganapati.

The Mantra must be pronounced distinctly and without mistakes. Repetition must be neither too fast nor too slow, and thought must be given to its meaning.

Lord Ganesha removes all obstacles on your path. He is the bestower of blessings and 'siddhis,' which are spiritual powers, but also the bestower of "buddhi," the light of intelligence, to guide you in the right use of power.

Generally “Ganesh Mantra” is chanted 108 times daily or whatever suggested by the Pandit or Astrologer.