Many people think the more arguments, the better. The opposite is true. You need few arguments but good ones. Anything weak is just an opening for objections and sidetracking. So keep minor arguments as backup.
Nothing impresses people more than being really listened to.
So, no matter how well prepared you are, be ready for surprises. Instead focus on solvable problems. Never impute motives. Use straightforward language. Ask for action directly rather than in the form of a question.