In your very first contract you will have a tutorial on how to use horses, boes, and swords. When it tells you to use the Bowmen, instead of taking control of them, use the Swordsmen to fight the groups of people. After fighting for about a minute you should gain a level. Repeat as desired to improve your men, making the start 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.