You will need enough miniatures of the appropriate race/type to represent the warriors in your army. lt is a good idea to work out your army on paper first and then purchase the miniatures that you require.

As you will see in the section called Warhammer Armies, each army fights in a particular way - some contain expert archers while others are better in close combat or have mighty magicians. When choosing which army you want to lead you could choose one that reflects your preferred playing style, or you could read The Warhammer World section and choose one that really captures your imagination. A good way of picking an army is simply to pick the one with the models you like the best.