Dear rideover,
The simplest book as far as I know, is Who am I? by Bhagavan
Ramana. No quotes from outside. All His experience. This was
WRITTEN and given to Sivaprakasam Pillai and hence no different
versions, no dilutions due to lapse of time. I read this book
everyday and it gives me the unadulterated guidance that has
helped me a lot.
Arunachala Siva.
Well, if people are afraid of trying ''the awareness watching awareness'' method -I don't blame them: the world is full of false masters-, Ramana's Self-enquiry method is good enough because it leads to Self-awareness, through the agency of Self-attention. Sri Sadhu Om explains excellently Ramana's Self-enquiry in his book, ''The Path of Sri Ramana'':
http://www.notthisnotthat.com/resources/The_Path_of_Sri_Ramana_Part_One.pdf
I will give some quotes from his book (pages 137-138):
''Just as the correct meaning of the term ‘meditation upon Brahman’ (brahmadhyanam) used by the sastras up till now is explained by Sri Bhagavan in the last two lines of the first benedictory verse of ‘Ulladhu Narpadhu’ to be ‘abiding in the Heart as it is’ (that is to say, abiding as Self is the correct way of meditating upon it), so also, the correct meaning of the term ‘Self-enquiry’ (atma-vichara) is here rightly explained to be ‘turning Selfwards’ (or attending to Self).''
''In either of these two kinds of enquiry (‘Who am I’?’ or ‘Whence am I ?’), since the attention of the aspirant is focused only on himself, nothing other than Self (atman), which is the true import of the word ‘I’, will be finally experienced.''
''Therefore, whether done in the form ‘Whence am I?’ or ‘Who am I ?’, what is absolutely essential is that Self-attention should be pursued till the very end.''
P.S. Sri Sadhu Om Swamigal tirelessly practised Self-Enquiry in a remote house 'Sri Arunachala Ramana Nilayam' in the interior of Thiruvannamalai for 30-odd years, and scrupulously wrote down the difficulties faced by him in Self-Enquiry and also the methods by which he overcame them.
http://www.nonduality.com/shankar1.htm