I mostly do sieges and take over their stuff and if I really just want peace, I will just leave some forts defended only with their small initial garrison so the enemy can take it back and then go back and forth between some fiefs taking them and letting them be taken. The only other way I know is to beat them so hard, they will not want to attack you. If you do have a good relationship with their king, the king will ignore any cassus belli, even if it makes his vassals get unhappy.
One way to keep other factions from going at war with you, is to have a high relation with their king. They seem to get it if you own some land that recently or originally was theirs and from random events saying some drunkard at a village mentioned how they are treated badly by their lord, so that can actually be used as a reason for war (this has to become part of Crusader Kings 2).
War is provoked a lot if the enemy gets to have cassus belli with you. Without knowing how M&B works under the hood, I felt over the time I played different mods that there are a handful of things that help when it comes to kingdoms going in peace.