In this section we will lay down a set of rules to follow in the opening stages of the game. While there are exceptions to every rule in chess, you need to be quite a strong player before you're truly ready to decide which ones to break. Until then, you should treat these rules like laws of nature - break them at your peril!
This is the absolute number 1 most important rule of the opening. In chess, Development means moving your pieces out from their starting squares ready for battle. Many players make the mistake of only bringing out one or two pieces and moving them around, and only bringing out reinforcements when the first few get stuck or captured. In chess, you need all your pieces in play to have the best chance of winning.
Time is of the essence in the opening - you can't afford to waste a single move. If one player can develop their pieces faster than the other player, that player is said to have a lead in development. Being ahead in development is a good thing because whoever has their pieces ready first can attack first. White has the first move in a game of chess, so usually white has a very slight lead in development to begin with.
Is there a particular order you should develop your pieces in? Well, knights and bishops should come out before queens and rooks. Usually you want to develop the knight and bishop on the side you want to castle before the other pieces, so you can get castled quickly. You should try and make sure that none of your knights or bishops are still on their starting squares after 10 moves.
You have to move at least a couple of pawns in the opening to let your pieces out. Usually, it's a good idea to start by moving one of your centre pawns two squares. Moving the king's pawn two squares opens lines for the queen and kingside bishop, so is usually the best choice for beginners. However, a lot of players waste time by making other pawn moves that don't help to develop their pieces. Here's a rather extreme example.
Wait a minute, wasn't the first rule to develop the pieces? So why not the queen? Remember, the queen is the most valuable piece besides the king, so you can't afford to lose her (unless you can get your opponent's queen in exchange). Early on in the game, that means your opponent has fourteen pieces which are less valuable than the queen. If you bring your queen out early on, your opponent can develop his pieces and attack your queen at the same time. You would then have to waste a move saving your queen when you could be developing instead. Here is an example.
It's absolutely vital to not waste a single move in developing your pieces. If you start moving the same piece around while your other pieces are still on their starting squares, you're losing time. The only time you should move a piece twice is if you need to capture an enemy piece - such as in this example:
It's usually always worth the time to capture an enemy piece other than a pawn, but sometimes its better to keep on developing your pieces and not waste time capturing pawns in the opening. Going pawn hunting early on in the game while your pieces are undeveloped can sometimes lead to trouble.
Once the pieces start coming out, the king will start to feel a bit vulnerable in the centre of the board. To avoid being a victim of a quick checkmate, you should try and make sure your king gets castled early in the game. Preferably, this should be before move 10. Castling also has the bonus effect of bringing one of your rooks to the middle of the board, where it can menace the enemy king if he has neglected to follow this rule!
The following game demonstrates the dangers of leaving your king in the centre for too long. It was played between two masters, Richard Réti and Savielly Tartakower, in Vienna, 1910. It goes to show even the strongest players sometimes get caught out in this way, but that's not an excuse to do it in your own games!
As you get better at chess, you'll start to learn that the most important area of the board is the centre - that is, the squares e4, d4, e5 and d5. Think of these squares as being like the high ground. Just as in real warfare, controlling the high ground in chess is often the key to victory. The ideal deployment for your pieces should perhaps be something like the diagram below.
All of white's pieces help to control the centre of the board, even if they aren't placed directly in the centre. Of course, this position is a bit of a fantasy, because your opponent will get to move too, and they will be trying to control the centre as well. You might not get to put all your pieces on the absolute best squares, but that doesn't mean you shouldn't try!
By connecting your rooks, we mean clearing the space between them so that they protect each other. You can do this by moving out all your pieces and castling your king. Having the back rank clear means your rooks can easily move back and forth along it - either for defensive purposes, or to support a pawn push. Ideally, you want to move them to the centre as in our fantasy position above. Placing a rook opposite the enemy queen is sometimes also a good idea, even if there are currently pieces in the way. Here is an example of what can happen: