Many comments have been made about the objectives of the opening play and perhaps the best advice we've heard is the one about being able to get to the middle game with a playable position. This ideally means that you have your king safeguarded, your pieces have decent mobility and scope, you also have sound pawn structures, and you have opportunities to create real threats to decisively win material or even cause a checkmate.
Most chess instructional books will list the following as important opening concepts to achieve the above:-
- Controlling the Centre
- Develop your pieces
- Safeguarding your king, ideal defence, maintaining the integrity of the castled king
- Hinder your opponent's attempts to do any/all of the above
The player who can get the job done quicker will usually be rewarded with a superior middle game position. Tempi is therefore a very critical factor in the opening. Every move counts towards securing key positions, getting another piece orchestrated into the attack and/or keeping the king out of harm's way. Many less skilled players tend to overlook the importance of this. So avoid making futile moves in the opening or attacking too early without sufficient attacking pieces or insufficient backup.
TEMPI is basically how to get there faster.
Some openings are deceptively passive and "quiet" favouring a slow strategical battle and gradually building up tactical opportunities which explodes later into the middle game. Some others are aggressive and explosive very early in the game abounding in tactical opportunities for both with lots of threats and counter threats. And, yet others get very quickly into the middle and the end game usually with a race for pawn promotions determining the eventual winner.
Find an opening that suits your style of play and let it well. Gambits and hypermodern openings are usually favoured by strong tactical players as they often present many exciting tactical opportunities.
Always remember, different openings to suit different style of play.