3 ideas
Xenophon argues to the officers that victory goes to the side whose souls are stronger, not the side with more men or better weapons. Soldiers who expect death and fight anyway tend to survive, while soldiers who try to save their lives tend to die. Leadership in a crisis therefore means restoring the will to act before any tactical plan can matter.
Without a paymaster, the Ten Thousand held assemblies, voted on routes and leaders, and called generals to account for their conduct afterward. Xenophon relied on persuasion in these assemblies but also insisted on obedience to officers, military hierarchy, and punishment of the disobedient. The assembly held the mercenaries together, though faction grew once the immediate danger had passed.
The Greek heavy-infantry phalanx could not answer Persian slingers, archers, and cavalry or mountain tribes who fought from heights. Xenophon responded by improvising a squad of Rhodian slingers and a small mounted troop, splitting the hollow square into flexible companies that could separate at bridges and passes, and sending detachments to seize high ground before the main body entered defiles. The method is to diagnose which enemy capability your standard doctrine cannot counter and build that specific capability out of whatever talent the force already contains.