Smile to indicate your acceptance and contentment. If you do not like something, do not hide it. Show that you care about the issue being discussed and that you stand behind what you say.
Have a cup of coffee
Coffee soothes your emotions and you will therefore less likely to start verbal clashes.
Emphasize that there is not too much time left
The more you can show that certain things will soon change in the way you think, the greater the interest of the other party will be.
Provide as much data as possible
If you want to convince, support your arguments with as much evidence as possible. In this case, quantity is more important than quality.
-kk-