The fundamental skill needed by all players is knowing how the pieces move. I know what you're saying, "Gee, I learned that years ago." However it's not that simple. Remember how beginners who have been playing only a week or two play? Do you remember how when they move their queen the will leave their finger on the top (touch move!) and look around to see if any enemy pieces can capture it on its new square?

Now that beginner knows how the pieces move yet he still takes a lot of time seeing if his Queen is en prise. And even then he often overlooks a knight lurking in the underbrush.

Much of a more experienced player's problem is similar. He knows how the pieces move but overlooks a knight lurking in the underbrush in a variation two or three moves in the hypothetical future from the position currently on the board. The skill of being strongly aware of how a piece moves can still be lacking, on some level, in even experienced players.

The first task in trying to get out of the rank beginner level is to have the moves of the pieces as automatic in ones perception. A beginner looks at a chess position and sees wooden or plastic figurines scattered in a pattern on a checkered board. He must exert effort to be aware of how all those pieces move. Often it is an arduous task: He chooses a pieces and looks at all the squares it can move to. To find these squares he often has to remind himself how the piece moves. This is a very inneficient process -- (1) choose a piece (2) remind onesself of how it moves (3) use the rule to find the squares it can move to.

The stronger player cannot look at a chessman on a square without being aware of its moves. As an analogy consider how children learn to read. When just beginning to read they will often look at a billboard and read a word or two. This must be a willed action with them. They first look at the billboard and then they decide to try out their new skill. At that point they decipher the shapes into letters and the letters into sounds and words. Adults, on the other hand, cannot look at a billboard without reading. It impossible for an educated adult to look at the pattern of the letters without being aware of their meaning.

This is the first level of skill that a chess player reaches toward. The perceptiv skill of having the moves of the men appear automatically in his awareness.