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It is not necessary to follow rules while worshiping, BUT, whether to follow rules or not depends completely upon whom you are worshiping. If you are worshiping some god or deva and any other higher or other realm beings, then following rules is necessary because without proper process they will not be able to take your offerings. And the second reason is that, most worships are done to have some material gain or fulfillment of some desires. These are effects, and for them to take place there has to be proper cause in terms of the process of the worship. So there are many do's (vidhi) and don'ts(nisedh) laid out for worships. But for God, the supreme being, the case is different.

If you are worshiping God, the supreme being, then there is no requirement of following rules if you are doing pure and niskama bhakti, that is, you are worshiping Him without any personal desires. This type of devotion is called as raganuga bhakti, which is done out of love.

But a person's heart needs to be clean and pure to a certain level until he can love and worship God for no reason at all. So in the beginning there are certain rules and regulations to be followed which act as a set of practices and increases the person's attachment towards God. This type of devotion done following proper rules of vidhi and nisedh as laid out in the scriptures is known as vedi bhakti. But at the end of the day, any such injunctions for worshiping God only server the purpose that you remember Him always and don't forget Him. So says the Padma Purana :

smartavyah satatam vishnur vismartavyo na jatucit
sarve vidhi-nishedhah syur etayor eva kinkarah

"Remember Shri Vishnu always, do not forget Him at any time." All injunctions and prohibitions of the scriptures are only but its subservient.

Camphor is not burnt to burn ego

I know it's said like this that we burn this or that for this and that, but that's hardly the actual reason. Camphor is burned because of its fragrance giving essence which purifies the air and the surrounding atmosphere of the place of worship. And there is a relationship between the air element and puja. The purer the air, the easier it would be to convey your worships to the realm of gods and higher beings. http://hinduism.stackexchange.com/a/653/38