Mapping in TF2.

For Starters you will want to plan out every detail of your desired map on paper or tablet drawn computer sketches.  Plan out the floorplan, where objects will be placed, everything.  Symmetry will be key because no one wants to play on a map that is not fair on both sides and trying to make it fair but not symmetrical is suicide.  Next either after or while drawing your map out learn the program you wish to use, or similar programs what will give you the jist of it.  Make sure while planning your map you indicate what the height limits will be as well as desired lighting effects (if applicable).  Learning the program is the toughest part obviously and there it comes down to finding online tutorials or purchasing dvd tutorials from steams online store which is pretty useful.  

If you want to get a quick taste of what its like without spending money go and download a powerful 3d Animation Program called Blender, it is a full version not a trial.  Or if you would prefer check out Autodesk 3Ds Max or Maya trials that last 30 days.  

When actually modeling the map itself you start out by creating the more broad features of it then polishing it into what you want it to look like exaclty.  

Originally Posted by Milky
The hardest part about mapping is the initial learning curve, once you get past that it's not as bad.  That being said, there's a huge difference between being able to make a map, and being able to make a good map, and I think that's what kSniper is referring to.  I have a couple of small tutorial maps in the custom map section that you can d/l if you want something to look at in the editor as well as an intro to the Hammer tools guide as well.  Plus there are a few decent mappers in the clan that would be more than willing to help out.