There are over a hundred meaning attributed to Om. One of the more widely followed meanings is that of the Omkar Swaroopi Ganapati or Ganapati as Om or Aum. Hence, Aum can also be taken to be one of the names of Ganapati.
The practice of invoking Ganesha before embarking upon any new venture or any important occasion or religious ceremony is a part and parcel of the Hindu Religion, so also is the age-old practice of commencing most Mantras with “Om’’.
Certain, advanced devotees of Ganesha, Meditate upon the Omkar Swaroopi Ganapati by chanting the Om Mantra, to get the blessings of Ganesha.
I have been told by these devotees that the “Om” Mantra starts becoming potent and effective and gathers strength, after the completion of Nine Hundred Thousand Mantra Chants.
If anybody wish to practice the Omkar Swaroopi Ganapati Meditation, it is my opinion that they visualize Ganapati as Om, while chanting the Mantra. They should also try to keep the mind free from thinking and expecting any rewards for chanting the Mantra and try to maintain a Satvik Lifestyle. If anyone one desires to use a Counting Rosary, they can use a Red Sandalwood, Tulsi Beads or Rudraksha Japa Mala for this purpose.