I am conquering the World right now,
for me the key was getting a City as Clan and building up my money before i even started an empire. i ran around trading and everytime a Kingdom declared War on me i just ran around searching for open field battles (alot of loot and money) to release the lords thereafter to build favorable relationships (then they are less likely to declare War on you - the problem here is there are usually alot of clans in one kingdom so it takes time)
i could also imagine that you shouldnt build an empire before you actually have a second gen on your hand as the Option to get allies through marriage seems to be the only option i can still think of to compete an all out war and prevent a multiple front war aswell as stopping the conspiracy.