Do not offer these things to Lord Shiva at Mahashivratri

Kewda & Champa Flowers

Shiva is although not very fond of white flowers, but, it is said that the flowers Kewda and Champa are cursed by the Lordand should never be offered to him during puja.

CoconutWater

You can offer coconut to the deity but do not offer coconut water. Yes, it does sound a bit strange but it is not recommended to offer coconut water to Lord Shiva, especially on Shivaratri.Everything offered this day is considered as nirmalaya, and cannot be consumed and, as consuming coconut water after being offered on deities is considered as mandatory to drink, it is therefore not offered to Lord Shiva.

Saffron or Kum Kum

Never offer saffron or kumkum on the Shivalinga. Not only on Shivratri but also in general, never offer it. The reason is that Lord Shiva is a recluse, and recluse people put ash on their forehead. And it is a universal fact that Shiva puts ash, not Kumkum.

Infected Bael Paan

Bael is one of the most sacred trees. It has a lot of medicinal properties and is known to be a cooling agent. Bael paan is his favourite but it should not be cut or insect-eaten when given as an offering.

Bronze Pot

While offering milk or curd to Shivlings, stay away from bronze pots. It should always be in a copper pot. Why? Because it is equivalent to pouring wineas per some passed down theories. Also, donot let your fingers touch the water, milk, and ghee because the touching of nails makes these things inauspicious.