This is the procedure for Vinayaka chaturthi vrata as told by Mahadeva to Lord Kartikeya.

Ganesha Purana gives a description of how Vinayaka Chaturthi vrata should be observed.
Originally how it used to be observed.
Now we celebrate Ganesha Chaturthi according to our convenience.
But it is good to know the prescribed method in Ganesha Purana.
Vianayaka Chaturthi vrata is a month long vrata.
Starting from the Shukla paksha chaturthi of Shravana Masa and ending on the Shukla paksha chaturthi of Bhadrapada masa.
This period coincides with the Simha and Kanya masas in Saura mana.
On the first day, the person who has to observe the vrata has to take bath in the morning and go to his guru's house.
He should worship his guru and offer clothes, ornaments, fruits, etc.
Then he should tell his guru that for him the guru himself is Lord Ganesha.
He should request the guru to guide him through the vrata.
The guru gives him upadesha of how to observe the vrata.
After this, he should go to a holy river nearby and take bath.
Then he should come back home and start the vrata by meditating upon Lord Ganesha.
The idol of Ganesha is made from clay.
How to make the idol, we have already seen in an earlier episode.
He should worship the idol every day.
The idol should be accompanied by either peacock or mouse as the Lord's vehicle.
The idol should be placed in a beautiful well-decorated mandapa.
Kalashas made of gold, silver, or copper wrapped with fresh clothes should be present inside the mandapa.
The kalashas should be filled with water from holy rivers and you should put gemstones and tender leaves of Pippal tree inside the kalashas.
The Lord should be worshiped with the 16 upacharas and offered apoopa, ladduka, modaka, panchamritam, and payasam in naivedya every day.
His guru would have told him which mantra of Ganesha he should chant during the vrata.
He should chant that mantra every day.
Ideally, he should finish chanting that mantra 1 lac times in that one month.
On the night before the last day of the vrata, he should keep awake and listen to the stories of Lord Ganesha.
On the last day, Ganapathy Homa should be performed.
Sahasra Nama should be chanted and neerajanam should be performed.
The guru and holy brahmins should be invited and worshiped.
Food should be offered to friends and relatives.
Then the vrata can be ended.
This is the procedure for Vinayaka chaturthi vrata as told by Mahadeva to Lord Kartikeya.