One important thing is to ignore most missions - almost every settlement your council wants you to conquer will eventually embroil you in a war with somebody else who wants it (Durazzo in particular which is perhaps the most worthless starting settlement on the whole map but strangely attractive to neighbours) and the rewards offered are almost never worth the hassle of conquering and defending the target (2,500 florins, 3 or 4 'best' units that you can recruit yourself if you really need).

Similarly instantly obeying the Pope means endless wars with everyone he falls out with - faced by a demand to blockade or break alliances I always wait it out and in most cases the faction will reconcile before the time limit expires.

Crusades are another matter - I tend to put all my out of date and surplus units on a boat under my oldest general and set off just before the time limit expires - then if he doesn't die en route, or the settlement isn't taken by someone else, you then starve it out on arrival and give it to the Pope or sell it to the highest bidder (the former owner will often pay you handsomely for it back and a ceasefire) after sacking and dismantling if in spite of everything you do manage to take it.

Such tactics are incidentally not that unhistorical - many more kings and nobles took the cross than ever went on crusade and their are several examples of crusades getting diverted (4th) or ending in bloodless negotiation (Frederick II).

Alternatively send a young general who needs the personality boosts and bring him back afterwards.