How to celebrate "Karthika Somavaram" ?

In Hinduism, the days of the week are associated with certain deities. It is believed that observing a fast or performing special Poojas for these deities on their favorite days can bring their blessings and many benefits.
Monday is Shiva’s favorite day. But Karthika Somavaram, or the Mondays in Karthika month (November-December) of the Hindu calendar, have special importance. One of Shiva’s names is Soma or Someshwara, meaning ‘the one who wears Soma or the crescent moon on his hair or head’.

How to Observe Karthika Somavaram?

On Karthika Somavaram, people wake up before dawn and have a holy bath in a river or pond or take a head bath at home. They visit Shiva temples and perform Rudrabishekam and Archana. They also offer Bilva leaves to the deity.
The fast is from morning till evening. It is broken by eating fruits or dinner. Some light diyas when the stars come out or light a 1000-wick ghee diya in the Shiva temple. They may also do Deepa danam to a Brahmin in the evening. Some devotees seek blessings from an elderly couple. This is believed to be seeking blessings from Shiva and his consort, Parvathi.

Karthika Somavaram Vratham Benefits

Fasting and performing Poojas on Monday elevates our consciousness which gets tuned into the higher realms. The planetary ruler of Monday is the Moon, which rules our minds. It is believed that if one performs Pradosha vratham on Mondays and meditates on Shiva, one can experience God and even attain siddhis. The Scriptures say that a person who fasts on Mondays till evening, feeds a Brahmin, and eats food after seeing the stars will receive Shiva’s grace.
By fasting on Mondays, one can gain mastery over the mind. Shiva bears the crescent moon on his head. This indicates that has control over the movements of the Moon. So he is called Chandrashekara.