What's his opinion of you ? Considering the huge buff you get to relations when you vote for someone, i'd say it's wise to spend your first 100 influence points voting for whatever your king wants, just to be sure he really likes you and will not try to screw you.
Also, trying to out-influence the king is kinda silly. He's the king. He makes choices. And with the current lack of civil-war/rebellions, there is no real consequence for the king to being an selfish arse.