Why do we worship Lord Ganesha first? Why Lord Ganesha is worshipped as First GOD?

Lord Ganesha’s name is taken before the auspicious beginning of a work or inauguration especially during Griha Pravesh in every Hindu household. Despite the presence of 36 crore deities, why Son of Lord Shiva and Parvati is worshipped first. An intriguing story lies behind this question.