One thing I like to do is to design areas that look attractive to campers, but provide only a false sense of security. For example, here we see some crates with a hollow spot inside. It looks like a great place to camp...
...but it is not. While a player hiding here is well-covered on all sides, and grenades lobbed into the hole will fall through the grating, this spot is completely exposed to fire from below.
LCDLC Mapmaking Dept.
Maps finished: Hellhouse, Sorry, Worrior 1-20
Maps modded: CubeOrigin
Maps in release candidate: Blockforts, Cannons 1, Hotzone, Icecastle
Maps in beta: Arctica, Cannons 2, Cerulean-River, Igloo, Skygarden, Spacestation
Maps in alpha: Merlin, Totem