So I decided to take the plunge and try making my first map.
So, where do I start?
There are so many tutorials and resources out there, where do I start.
Well, I found a step-by-step walkthrough about creation of a simple but playable and winnable map.
    First, let's create a couple of basic, connected rooms that we can run around in.
     
  1. Read Getting Started to familiarize yourself with the Radiant tool and 10 Lessons for some practical and time-saving lessons learned by this newb mapper
  2. Read through the basics of construction, then make a basic room
  3. Compile your room by following step 10 and 11 in the previous tutorial.
  4. Clone the first room then connect the two with a hallway
  5. Pick one of your main rooms and add a smaller room against one wall (like a control room) and add some windows you can shoot out
  6. Go to Drakir's Prefabs, download a couple of prefabs and unzip the contents to your [mapping environment dir]/etmain/prefabs folder. From the main menu, select: Edit:Load Prefab. Navigate to your prefabs folder, select one, and hit Open. Position your new prefab.
  7. Add a rotating door to separate the first room from the hallway
  8. Compile your map and try out your new door, breakable windows, and prefabs.

    --- Now take a DEEP breath ... and let's add something for our engineers to do:

     

  9. Add a constructible door to separate the second room from the hallway
  10. Add a destructible objective

    --- That wasn't so bad. Now, let's bring the map to life (make your constructibles constructible and your destructibles destructible) and write your map script

     

  11. Add a script_multiplayer, create your map script, compile, and test your new constructible
  12. Write a victory script
  13. Compile and test your new constructible door and destructible objective
  14. Read Nib's article on Detail vs Structural brushes and Hint brushes
  15. Pat yourself on the back. You now have a playable, winnable map.

Alternatively, after Step 8, you could download and insert my "map-in-a-box", reposition your entities, compile, and try it out.