diplomacy related tips/strategies?

[Myth]

As soon as one of your Catholic enemies gets excommunicated call a Crusade on their farthest settlement and steamroll them. Papal standing + dead Catholic. When I used to play vanilla M2TW my usual choice was Milan due to them being so berzerk all the time.

[Vampiresbane]

As soon as one of your Catholic enemies gets excommunicated call a Crusade on their farthest settlement and steamroll them. Papal standing + dead Catholic. When I used to play vanilla M2TW my usual choice was Milan due to them being so berzerk all the time.

There's a lot going on with Diplomacy and about a year ago I set out to write a guide about it in order to understand it more myself and to share what I learned. It's not in these forums, but could prove really helpful to you guys and this thread.

Vampiresbane's Art of Diplomacy Guide

[Handel]

The assassins are very powerful "diplomats". Even the newly minted assassins have at least 5% chance to kill any person. So a squad of about 10 assassins can kill anyone in 1-2 turns at most. Excommunicated? Send the assassins. The Pope is a PITA - send the assassins. Playing as an orthodox nation and going to kill the last general & king of a catholic nation? Send the assassins first and kill them before attacking.
But not sure what to do with the foreign princesses - do the AI try to make alliances or try to steal the human generals?