Hi, two time iron dm champion here and honestly i should have won last year had I provided one more social encounter and the winner had not had two extra players) GRR still bitter....
In any case, this is a very fun event and I do plan on doing it again this year. I won't tell all my secrets but I will suggest that you really make sure you understand timing and don't get too convoluted with your plot. Don't be too sticky wit hit too. A lot of the tournament is figuring out what the players game for and giving it to them in the four hours.
I've seen a lot of bad DMs come through the tournament. I mean bad. And they may be fine dms at their home, but they get too stuck on their plots, they have no original ideas of their own and they are bad at timing.
Remember to give your pcs a beginning and an end, even if it's a negative one. If you got this amazing story and you realize time is getting short start condensing it. I've seen some really good DMs just get tangled up and run out of time, so the pCs in their game get no resolution of their adventure or what anything was about.
This year we are also doing an iron pc tournament if you want to get an idea of how iron dms DM. As I was writing the adventure for it i thought, man if any dms participate in this they will get a good understanding of my thought processes and how i compose my winning adventures. My biggest thing is that i hate lineear. If the pcs aren't directing the story i am not doing something right.