A few key things:
#1. Use the grid. There are a lot of brushes that are off by 1 or 2 units. Lots of hovering rocks and edges that don't meet up correctly. For the large rock structures and outdoor area, you should be using a grid size of at least 32.
#2. Pick a theme and stick with it. Don't try to use every rock/sand/whatever texture available. Pick a couple that work together and make the appearance of your map consistent. It doesn't make sense to have one type of rock in one place, then 20 feet away, have a completely different type of rock that could not realistically be located within thousands of miles.
#3. Keep the textures/structures realistically plausible. For example, would you build support beams out of planks of boards? That doesn't make sense -- it wouldn't have any structural integrity, especially when the grain is vertical and the beam is diagonal. You'd want a solid chunk of wood, with the grain going along the length of the board.
That being said, it's OK for a first map, but as a general rule, first maps aren't really public material. They're a learning experience, and once you have a better grasp of mapping, you can make a map like your first map, but better, in probably less than an hour.
You've certainly made some improvements from the first version. It's still too box-like, though. The added brushes on the walls help, and sometimes you can get away with that (midnight, midnight2, and bombsaway have outdoor areas like that -- basically a box with some funky rock brushes added on to make them not look like a box). What you have, though, is too large to cover up with tricks like that, I think. You need to actually vary the shape of the entire map itself. Give it some character.
I'm not sure if you're using it or not, but clipping planes are extremely useful for making arbitrary rock structures.
Another thing you have to watch out for with large, open maps like this is that the compiler will chop brushes up into lots of polygons. This was done for the software renderer, but we're stuck with it for the moment. Too see this in action, type at the console:
deathmatch 0
map <your map>
gl_showtris 1
I've attached a screenshot showing this. You can reduce the chopping by scaling the textures up. The brushes are chopped based on texture units, not world units, so the larger the texture is, the less it will get chopped up.
I'm not sure about the game play on this map. I think some teams may have a significant advantage over others. For example, the blue team spawns on the high ground and has lots of small rocks for cover, but other teams spawn in a cornered position with little cover and opposing teams on each side. It might be better just to make it a deathmatch map.
One thing I would honestly suggest, rather than trying to fix all the little misalignments, is to simply remake the map from scratch. If you keep working with a large grid size, it should be easier to redo the whole thing than to fix the errors. Then you can also alter the shape of the map to make it not a box.
