[Ragerider]

My initial problem with diplomacy was that I was trying to use the cards I had to answer the npc I was parlaying with. After a bit, I figured out the cards I play don't make a difference to the parlay except to give me points. So, while I read the stories, they're pretty fun, especially the dark elf starting diplomacy, I look at the cards I have and try to keep the ball on my side of the bar.
Point being, just use the cards you have available to keep the ball on your side of the court. A lot of times you'll have to go through the parlay one time to see what the npc is playing and adjust your card strategy accordingly.
Don't know if that helps at all, but when I thought of it in those simple terms, it became a lot easier.