When I first started mapping I had quite a lot of quake mapping knowledge and the reason I liked mapping in quake was that the compile times where Nil and the game ran/loaded up Very quick, And also mapping was fairly simple in it.
But the fact that Quake and Source use pretty much the same editor go me into mapping for it
This is why I am posting this tutorial on my website because it helped me SO much and I owe all of my mapping skills to it:
Some of the stuff in there is outdated but the brushwork and texture suff is pretty much that same as modern day hammer:
** One of the most important quotes from this guide**
Great levels don't happen by mistake. Paying close attention to all the details in your map will make a difference. Lighting, architecture, texture choices, texture alignment, scale of objects and areas, object and entity placement and more. Hallways don't have to be just 4 plain surfaces, try adding some details or angle the walls slightly, ribs, light fixtures, or access panels, anything to add detail. Try to come up with something nobody has thought of, good architecture includes good detail. Spend some time studying other levels, id's Rituals, etc. They put in the time and details that make levels great, and now it's your turn.