The Bretonnia army is made up of different types knights which have good saves, cheap bowmen, and can have mass ranks of infantry if they want. One main thing about Bretonnia is the amount of Knights which area available to them. For this reason they should be the main force of the army. One trick used is to create one or two large units of Knights of the realm and then get two other units of some types of Knights and a powerful flying creature. The next step is to deploy your realm knights so that they will be able to march down the middle of the battlefield while you deploy one unit of knights on the left side and one on the right while the flying monster is behind cover. It is a basic flanking attack but executed well it can win a battle. One main problem with this is the enemy being able to tackle each unit by it's self so you should generally try to move in for the kill all at once. One major problem for Bretonnias the fact that they don't have a cheap elite units in their army unlike others i.e. dark elf which elfs,wood elf wardances etc... To deal with this increase the value of one unit of knights or infantry by adding in powerful banners and champions with good magical items which help the unit i.e. amulet of fire, blade of couronne this way a powerful unit can be created and masses may be use