Just as Om is the Vedic mantra which is added to the beginning of every shloka, similarly, one must do the puja of Lord Ganesh before one does the puja of any other God. This is a boon granted to Lord Ganesh by Lord Shiva himself!
The names used to refer to Lord Ganesh include the following: Vakratunda - one with a twisted trunk. Mahakaya- one with a huge body. Koti Surya Samaprabham - one who shines like ten million stars. Vighnaharta - one who removes all the obstacles. Riddhidayak - one who has the ability to grant great wealth. Siddhidayak - one who has the ability to grant all wishes.
According to Narad Puran, "...those students who desire knowledge, or those people who desire wealth, or those who have no progeny but desire children, will have their wishes and desires granted by doing the puja of Lord Ganesh."