1. If you build it, they will come!
Do not feet if interest seems low by only a few responses. Once posted, tuners will show up.
2. Research!
You have seen plenty of challenges and have tested. But building and posting are a little different. Check passes challenges, see how they were posted and come up with your own game plan. Best to start with several posts, just respond with 'reserved' on each first. Then you can go back and edit each, this way no one posts in between posts.
3. Rules and info!
Even if you think everyone should know, post it anyway. The more information you put in the OP the better. Eliminates questions and confusion later.
4. The unexpected!
Few challenges go by without something coming up for the host to deal with. It happens, but how you handle it makes all the difference. Firm, stern, yet gentle in speech always works best. As host, it's your challenge, so run it that way.
5. Fun.
Have fun with it, and never be afraid to ask for help or assistance. More than enough people will be willing to lend a hand when needed.