Getting married nets a handful of points. Once you establish your own kingdom, you can earn a few points as well by being recognized by the other rulers. You can curry favors by sending gifts such as horses. Once your kingdom's relationship is around 20 or so the other faction will likely recognize you as long as they are not interested in your fief; i.e. they are at least two factions away on the world map or they are not the same faction from whom you conquered your own territory from. When sending an envoy with gifts, select the party member with the highest persuasion points just as you would with any other negotiations. Additionally you will also earn RTR if you are king of your own faction and you manage to negotiate a peace with another faction that is at war with you. Sometimes, I deliberately conquer the enemies richest town and then I ask to negotiate with the faction king. Often times, they will demand that you return that town plus some gold. It gets expensive but it can be the only option if another faction declares war on you and you don't want to fight on two fronts. However, do bear in mind that having high RTR does not absolutely guarantee being safe from attack. There a lot of factors that decide whether a faction will go to war; things such as the current state of the map, faction's weakness, the personal relationship between the player and the faction king, etc. Ultimately, each faction will try to conquer everything. That's what the game A.I. is programed to do. Just because you are on good terms with a faction does not mean that they will never declare war on you. I've had 50+ relationships between my own player faction and another and got surprised when they declared war in a matter of months.
