/vr/ - Retro Games

I followed the Doom Builder 2 tutorials listed on the site and watched some additional ones on youtube.
Messed around and made some box rooms, figured out how to place lighting and doors etc.
After that I hopped into Knee Deep in The Dead and took a look around.
Now that I have a little bit of an understanding I paid more attention to lighting sectors, detailing textures, thing placement and all of that good stuff.
I noticed how a lighting sector originates from the open window in the room with the toxic waste and how it breaks up the environment, or how the flickering light before the exit room has a lighting sector that goes through the partial wall to make it look like light is flooding through the holes in the grating.

What I'm getting at is that I feel like a brainlet. I would have never thought about those kind of details and now that I'm actually looking for them I noticed that they're everywhere.
How do I learn to go from boring boxes and corridors to maps that are actually enjoyable to go through and explore?
I've never really given much thought to map design.
It seems way more complex than I realized. Military Base seems like the most simplistic map of episode one, being primarily a 3x3 grid of rooms but even those are broken up with side areas, pits, details, connecting passages and such. Then I look at Toxin Refinery and I just think "Damn."
It feels kind of daunting.