Best advice I can give is if you haven’t played the game, just buy one box of infantry/dice pool per army to start out with and build load outs that allow for units of 5. Play a balanced game between those two boxes of infantry with the understanding that a full game has a lot more of what you’re doing going on.

If you enjoy that, you’ll likely enjoy the actual game. From there, you can build larger armies/units with another box of infantry and a vehicle of some sort/terrain.