Sicilian Defense Basic Themes
(Arlington, Texas, USA)
Sicilian Defense, Najdorf Variation
First and foremost, time is the most important factor in the Sicilian Defense. Many times you might be tempted to play Qa5 or play pawn a6, but be careful to make sure that you have the time to do it! By this I mean, keep an eye out for a few simple plans that White might have. Is White about to occupy d5? Is White about to open the h-file with a sacrifice. Can you breakthrough with pawn d5?
In any event, if you answered 'no' to all of the questions above then is probably safe to play Qa5 or pawn a6 or some other move that might not be in the main lines. Of course this assumes that you have started to transition out of one of the main lines. In the Dragon variation, for example, Qa5 may be a part of most main lines. Likewise, in the Najdorf pawn a6 may have already happened.
The point here is this, within about 15 to 20 moves you will very likely be in uncharted territory. If White is on the brink of a break through, then you need to have a very clear reason for each of your moves.
White's main opportunity in most Sicilian variations, is to get a quick and devastating attack on your king-side. Your main opportunity in most variations is to get a lot of counterplay on White's queen-side, and perhaps a good attack if White castled queen-side.
Also, never forget that you probably have a better pawn structure than White. This is very important. It means that you can often trade down to a better end game.
Finally, try your best to engage in aggressive play. The Sicilian Defense often rewards Black if he is sufficiently aggressive. Last, but not least, try to have fun!