These are the basic guidlines that should be followed for any duel. Not set in stone, but a decent guide to make for a better duel:
1- In you first post state:
->Where duel takes place
->When the duel takes place
->Whether Magic is permitted
->Whether NPC's are permitter
->Who you are challenging
->Your character and possibly a brief bio
2- Always remember that you cannot directly influence another character, therefor you cannot kill a character unless you put them into a situation they cannot avoid.
3- You are not all powerful!
4- Other members should not post in Duel untill it is over, because they are private and do not need spectators. Watching them progress can be interesting, but please do not comment untill it is over or if you have good readon.
5- Have fun and enjoy yourself ^_^