Many wargames work of a point system- each player has a set number of points or value to buy units with enabling each player to field different armies, yet being balanced and fair for the game.
Just what you spend your points or battle value on depends on the narrative of the army, and what you are looking to play- is this a narrative based game, or something a bit more competitive, like a tournament?
The units you select are the LIST- and there are many ways to build a list.
One way of building a list, is to OVERLOAD your points all in one phase of the game- but this tactic is not for the weak of heart, while it is very powerful, one mistake, or slip for your opponent to counter will find you at a huge disadvantage.
Begin by breaking down your game system regarding turns and phases- an example being a game that has a movement phase, shooting phase, psychic powers phase, and assault phase.
With an overload list ALL your points go to buying units that are hyper-powerful in only on of these phases.
Take only units with big-powerful guns, and massive attack ability.
Units so fast nothing can catch them and they can strike anywhere on the table.
That’s not to say these units won’t have ability in the other phases of the ruleset- just that it is not the primary focus.
The focus is being so hyper-focused that your opponent can’t counter that phase of the game your army operates in- while using your hyper focus of that phase to beat them in all the other phases of the game.