need some help creating a campaign...

i need to know where to start... im not sure what all i need to edit with the triggers and settings before i can really start working on it... anyone care to explain the steps to begin working on a campaign?

thanks in advance

This is what im doing for my campaign.
1:I sit down and write a story(youve probably done this allready)
Design the maps first.
make character list etc.
2:then I make the map, no units or doodads besides trees and caves.
3:I add extra doodads and then add the units/buildings/creeps and if you are making any custom units do it now.
4:I put in the cameras
5:Then regions
6:Then i do the triggers
7:Finishing touches like add/remove doodads repostion a few thing and name the map.

if you do all the terrain first on all the maps then I find it simpler.
But all the units do 1 map at a time.