How do we observe Mahāśivarātri at home?

fast as you are able, worship Śiva with water, milk and bilva, chant through the night as far as you can, and break the fast the next morning.

Mahāśivarātri falls on the Kṛṣṇa-pakṣa Caturdaśī of Māgha (Amānta) or Phālguna (Pūrṇimānta) — the same night, named differently. It is the great night of Śiva, kept with fasting, worship and wakefulness (jāgaraṇa).

At home: fast during the day on fruit and milk, or eat once simply. In the evening do abhiṣeka of the liṅga with water and milk, offer bilva, dhatūrā and white flowers, and chant “Oṁ Namaḥ Śivāya”. Traditionally the night is divided into four praharas with a pūjā in each; families often do one or two, and spend the rest singing bhajans, reading the Śiva Purāṇa or the Śiva Pañcākṣara Stotra. Break the fast next morning after a final pūjā.

Children, elders and the unwell can simply do the evening pūjā and sleep — Śiva is Bholenāth, the simple-hearted Lord.

Tradition says a hunter, lost in a forest on this night, climbed a bilva tree to escape wild animals. Staying awake, he idly dropped leaves — and drops of water — onto a liṅga below. Unknowingly he had kept the Śivarātri vigil, and Śiva blessed him.

Source: Śiva Purāṇa · Four praharas of night worship

Dharma Q&A — worship at home · Ask a Jyotishi your own question