Yes, never forget about your diplomacy. it really REALLY does help when secession comes. its also nice to make sure he is not to old/young, and be careful what you do when you are old. if you inherit a kingdom at war, along side all the angry vassals, they see the war as a perfectly good opportunity to strike!. if you get ill/injured and your over 50, i tend to just quit all my wars, and live it quietly till i die