MTW: SWM, King, seeks companion for friendship and starting a dynasty

[AntiochusIII]

There are many ways to increase king's influence. I know only some of them, and their uses depend on your style.

1) Conquer, conquer, conquer. It doesn't matter who lead the conquest, the influence belongs to the King. Of course, this would eventually end up against your original intention to increase king's influence, as the AI does turn against you when you grow too big. They were created to trouble the player, after all.

2) Crusade. It is the most popular one. The king is guaranteed +1 influence (and +1 piety) if the Crusade succeeds. Not to mention some goodwill from the pope and whatever order knights (the equivalents of chivalric knights, but untrainable and available in early) you've got when the crusade starts. If it fails, however, expect a civil war, unless your king was really highly influential.

3) My favourite one, though the hardest to do. This one is mostly for turtlers (i.e. players who did not expand across the map, but establish themselves at some point for a long time, some even for the rest of the game. A popular tactic for GA mode.) Try to save an ally from a siege. How? Simple: if you have a border with, or a sea lane to, an ally's province that is being besieged (trapped in the castle) by your mutual enemy, march your forces in and save their arses. This will make your king more influential. It is especially useful if you have weak allies holding off against rising superpowers you wish to weaken.

Oh, and about the princesses. If you don't want to (or couldn't) find a foreign princely husband, marry them to disloyal-but-skilled generals. Though you can wait until the last year to do so, taking advantage of the princess' ability to act as a diplomat/scout.