I generally find that maintaining overwhelming force right at the border has a tendency to keep allies in line though... It just has to be really overwhelming, enough to crush their army like a bug.

I've also had to maintain a fairly serious navy though, or Portugal decides to see if they can harass me at sea, even though it's clear I can march on their capital and have it in flames within a year.

Still, I've had a really good run this time with the Moors... I haven't been at war with a single faction yet, and I have timbuktu and Arguin, Tunis, and Tripoli. Basically I headed south and east immediately and only reinforced Cordoba with militia units. By creating a full stack army of militia there I've managed to keep Spain and Portugal in line while I moved. I ignored the mission to take Valencia, preferring not to split my forces in the Iberian Peninsula, and instead sent troops to Timbuktu and Tunis at the beginning of the game...

I've also taken the islands of Cagliari and Ajaccio because the council of nobles demanded it.

I converted every settlement except for Tripoli and Granada to cities, for the economic boom. My merchants in Timbuktu and Arguin are pulling in almost 3000 florins per turn and I'm riding a wave of money.

I'm basically going to fortify my borders and wait to be attacked, so I can keep my "very reliable" reputation :D