When you have finished ...

When you have finished analyzing all the variations and gone along all the branches of the tree of analysis you must first of all write the move down on your score sheet, before you play it.
 Alexander Kotov

Quotes from the same author

I soon realized that it is not enough for a master simply to analyse variations scrupulously just like an accountant. He must learn to work out which particular moves he should consider and then examine just as many variations as necessary - no more and no less.
 Alexander Kotov
My achievements in the field of chess are the result of immense hard work in studying theory.
 Alexander Kotov
I can remember a case where Capablanca worked out an impressive combination, but then chose to make a simple move in answer to which his opponent resigned at once!
 Alexander Kotov
You will already have noticed how often Capablanca repeated moves, often returning to positions which he had had before. This is not lack of deciciveness or slowness, but the employment of a basic endgame principle which is 'Do not hurry'.
 Alexander Kotov
All candidate moves should be identified at once and listed in one's head. This job cannot be done piecemeal, by first examining one move and then look at another.
 Alexander Kotov