Yes all the zeroy links have good information and should tell you all you need to know to make a good map. As you go along and test things recommended that you try it on different mods, especially big ones, and not just the stock modwarfare mod. It will let you know early if you start to run into compatibility problems and what to focus on.
Common pitfalls: Too many custom xmodels, fx, images, memory (ff file size), various script errors. The bigger the mod the faster these will show up. There is a good map, had an F117 I think, that is very nice. It looks simple enough especially compared to some of the really complex maps out there but it was made in such a way that it is incompatible with almost everything but modwarfare.
A note about xmodel limits. The worst offenders by far are the exploding cars. Unless you really need them for something special replace them with simple static models.
Oh and if you run into script errors in the console, please fix them. Even if you dont see any actual problem anywhere. It will make things look more professional. ?