In your very first contract you will have a tutorial on how to use swords, horses and bows. When it tells you to use the Bowmen, do not take control of them. Instead, use the Swordsmen to fight the groups of people. After fighting for about a minute you should gain a level. You can do this as long as desired to better your men, making the beginning of the game easier. You can switch to the Horsemen to also increase their levels. When you feel you have their levels high enough, switch to the Bowmen to finish the tutorial.