Consciousness, no matter how well defined, is yet another concept that spiritual seekers have to live with. Understanding what consciousness is and what is not, can never be complete unless the intuitive knowingness gets involved. Put simply, you have to become consciousness to know it; being conscious is never enough. That’s why it is of critical importance for anyone on the path to Liberation, to “get it right”, thus avoiding spiritual errors and erosion of earnestness. The solution: finding a spiritual teacher of proven integrity.
In my spiritual library, it is Sri Nisargadatta Maharaj who takes the leading role. His message comes loud and clear: “You are the consciousness, all the titles of the Gods are your names, but by clinging to the body you hand yourself over to time and death – you are imposing it on yourself.”
Video of one his Satsangs, one of very few in existence:

Nisargadatta Maharaj\’s Satsang

Depending on one’s level of spiritual awareness, the “understanding” or rather an interpretation of consciousness varies. Whilst for the great majority of humans, consciousness is something that makes us able to use our senses and recognize our existence, for the spiritually inclined people it means much more. From seeing it as an imaginary ether that is the building material of the Cosmos, to equating it to the Self, God.
Still, even those of advanced spirituality have problems to grasp it.
Said Nisargadatta Maharaj: “When one talks of consciousness, one is likely to think in terms of an individual. But understand that it is not really the individual that has consciousness, but it is the consciousness that assumes innumerable forms. I keep repeating that the average person will not understand this. Why? Because it is too simple! To grasp, one wants something, some form, some shape.”

What a relief to know that the real “you” is not responsible for your body and mind; not in spiritual sense, anyway.
Ultimately, one wants to escape consciousness and become pure, or infinite consciousness. This is the domain of sages and realized masters. In the words of Nityananda: “Once one is established in infinite consciousness, one becomes silent, and though knowing everything, goes about as if he does not know anything. Though he might be doing a lot of things in several places, to all outward appearance, he will remain as if he does nothing.” To be there is to enter the gate to the Absolute…

If this is not a strong enough reason to persist in trying to there, hear Nisargadatta Maharaj’s words and understand that dwelling in the “ordinary” consciousness means nothing but bondage: “So long as consciousness feels the need of anything, you will be compelled to do it. When consciousness leaves, there will be no more bondage. Other than this sense of presence, which we have because of consciousness, what has anybody got? The real happiness, without its counterpart, can only be there when consciousness leaves. So long as consciousness is there, so long is happiness and unhappiness there. Pure happiness can only be there when consciousness is not there.”
To me, Nisargadatta Maharaj is the teacher of consciousness. His books: “The Ultimate Medicine” and “Consciousness and the Absolute”, both containing teachings expounded in the final years of his life, make understanding of this difficult subject, possible. More importantly, when fully absorbed, they become an encouragement to drop the final vestiges of intellectualization and begin to unravel the Knowingness that leads to THAT.
Finally, you can find free spiritual books by following that link; well worth exploring.