Lord Shiva, the greatest yogi and Lord of meditation, is revered in all sects of Hinduism, in all regions of India. It is traditional that every deity has a particular day of the week devoted to them and devotees observe a day of fasting and perform puja to the Lord on this day.
For Lord Shiva, this day is Monday or सोमवार. The particular puja for the Monday fast for Lord Shiva involves mantras, yantras and chanting.
Wake up before dawn, take a bath and wear white colored clothes. Then, sit on a traditional prayer asana with an image of Lord Shiva and this yantra in front of you. Arrange some sandal paste, rice, white flowers, dhoop, diyas, dhatura fruit, bel leaves, black pepper etc. for the puja. Then, meditating on Lord Shiva, repeat the following shloka while offering flowers to the deity.
karpoor gauram karunavataaram, sansaar saaram bhujagendra haaram
sadaa vasantam hridayaaar vinde, bhavam bhavaani sahitam namaami
कर्पूर गौरं करुणावतारं, संसार सारं भुजगेंद्रहारम् |
सदा वसंतं हृदयारविंदे, भवं भवानी सहितं नमामि ||
After repeating the shloka and offering flowers, chant the Shiva chaalisa. At the end of the chaalisa, chant the ‘Om Namah Shivaaya’ mantra 108 times with a mala made of tulsi beads or white sandalwood.