Getting a lead in development, by being efficient about how we develop our pieces, is the main aim of the opening.
How can you be efficient about development? For a start, think about how you can mobilise all of your pieces quickly, not just one or two. Think about where you can move your pieces so that they are doing something that influences the important central squares. Don’t make the common beginner’s error of moving the same piece more than once in the opening, unless it is essential. Think about where your king would be safest and make that happen as part of your opening strategy.
The game below is a classic example of what can happen if one side gets a lead in development out of the opening. Take a look at the position after White’s 12th move. White’s opening has not been a great success. His king is still stuck in the centre and he is 2 moves away from castling. In contrast, Black has castled his king to safety and has all his minor pieces ready for action and is 1 move away from connecting his rooks. To take advantage of the lead in development, Black needs to move fast. He realises that, to attack the enemy king before it has the chance to castle, he has to open lines to the king, and he invests a piece to do that as quickly as possible. By the 19th move, White’s centre is completely destroyed, and it is only a matter of time before Black’s better developed pieces move in to finish White off.