1. Focus on training new Troops at the beginning of the game until you have enough Troops to fill up the March Queue.

Promoting Troops helps you to obtain high-level Troops faster. The resources and time required for the promotion are the difference between the current and the next level.

Hint: Promoting Troops during the Hall of Chiefs and Alliance Mobilization will grant more points.
Why you need high-level Troops:

(1) Troops at lower levels will fill up your Infirmary faster during a battle.
(2) A smaller Troop of a higher level is more powerful than a larger Troop of a lower level. (Example: Beast Hunting, Castle Battle, Crazy Joe)