Always keep the council as your puppets. And you never have a problem with them.
Otherwise, even the happiest council will often disagree with you, especially when you need to declare new wars while other wars are still being fought.
I even intentionally don't abolish council power when I could, so that I can pass a new law every 5 years instead of 10.
Get 3 new council members, as courtiers instead of your vassal clan khans. Bribe them to support on council. You now own the council's majority vote for next 3 years. They will be forced to agree to any action you do.
I keep my best stat chancellor, martial, sward, and spy master. And they can all disagree with me.
On the other hand, I replace two advisers and chaplain every 3 years. That gives me 4 votes including mine, and I break the tie.
Vassal khans want to be on the council of course. And I let them on if I can. But if they are not happy because they couldn't get on, well, clan sentiment can be compensated with my high prestige. And some bribe can keep the khans always happy as babies.