question about making maps
 

when making a map do you build the ground and wall first then the sky and then add buildings and stuff to it?

its all personal preference but i would suggest this....

1. using topview make all your floors to give you a birdseye layout of buildings.
2. add a simple wall to border in your map.
3. do your ground to fill around buildings
4. build up all your buildings
5. do any terrain
6. put in all your shrubbery
7. fix up your borders and add a skybox

r3mix

I usually build the skybox first, for testing purposes, but you can do it in whatever order.

is there any way to have a skybox around your map but make it sort of invisible in the editor so that you can easily select stuff inside the box?

ie skybox is the outermost brush in all views and is selected whenever you click.

r3mix

Just select the brushes in the 3D view, then the skybox wont be a problem

I use real life Landscapes for my map... I usually start with the enterance of the area, and just add on to it, room by room. After I have the whole level done, I'll add things like pipes, posters, tables, doors, and windows. Do it what ever way suits you. As long as it compiles, you've done it right!