The Art of War
The Development of the Greek Tactics
1) The Greek Phalanx
For ages warfare basically went on this way: 2 opposing group of men did a lot of yelling and showing off. The site that shouted the loudest won. (Or they won when the other side got bored.) With the coming of larger civilisations warfare became trickier. It was noted that killing your opponent did much to impressing the enemy. After a while people noted that forming large blocks of men with spear worked quite well. Eventually the Greeks perfected this spearmen blocks and they became the hoplites that formed the Phalanx. The race started to show off who had the longest spears.
2) Cavalry & Light troops
The sides and back of a phalanx are very vulnerable. Therefore holding your flanks became very important in this kind of battles. In the race whom would outflank whom, you had better put your fastest troops on the flanks. (Also see Flavius Vegetius renatus advices. He also mentioned to use of reserves behind the centre and flanks.)
To disrupt the formations of the enemy and to slow any advance light troops armed with missile weapons were placed on front of the enemy. But when the going gets though, the not so though light troops get away from main parts of the battlefield.
3) Thebes Tactics
Still the Phalanx battle was nothing more than pushing and shoving between large hoplite units. The Thebans concentrated the toughest troops on one side of the phalanx line. This way they tried to break one end of the enemy's phalanx and thus be able to roll up the whole enemy line. The light troops en cavalry had to hold up the rest of the phalanx.
4) Macedonian Variations
The Macedonians had another way of ending the stalemate between the opposing phalanx units. They used their excellent cavalry to puncture the enemy line and try to get behind it.
5) Further developments
The successors of Alexander the Great further detailed the strategy. They used heavy cavalry to puncture the enemy lines, backup by light cavalry. The light troops used as shielding units and missile units. New in their strategy is the use of elephants to disrupt the enemy's cavalry and phalanx. At this stage the phalanx, that had been the backbone of the Greek tactics, was now only used to hold the enemy.
See also Polybius on the Phalanx: <here>