Play to your side's strengths
The asymmetric nature of the game means that you're going to have to learn how to play as two different factions. The king and his knights are strong, capable of pushing citizens and assassins out of the way, and moving as a single, difficult to attack unit. On the flip side of that, the strength of the assassins comes from the fact they're hidden. That gives you plenty of chances to bluff your enemy into wasting their energy on citizens rather than the killers in their midst. If you know how both sides play, you're going to be in a better position to work out your opponent's strategies, so make sure you get to grips with both sides of the titular fight.