cactus> hey, dont knock. We all started somewhere, its people like you who discourage new mappers. So if you cant stop trolling dont post.
oblivion> Looks alot better than the last set of screens. Ill give you a few quick tips which will hopefully make stuff look better.
as you can probably see, the box textures are messed up. To remedy this, shift+click your box (so highlight it) press S and a window will come up called "surface inspector". On the window there will be lots of different buttons, two of the buttons will be called "fit" click on the top one (not the bottom) and then the texture on your box will fit. If you ever need to change the texture back to normal click on the button called natural.
Your lighting is pretty good in most of the rooms, but the human base looks too bright, so lower the light intensity. Lighting is very important in a map, it can add mood, and really effects how good a map looks. Any map can look terrible because of bad lighting. Also, experiment with lowering the light altogether, it would add a darker mood and make the map look alot better.
Your walls look a little bare so add some stuff to it. If your struggling, add some support structures. You know in ACTS, outside, the wall and the bunker have those bits sticking out of the wall. Use something like that, it really helps make walls look a little more interesting.
Add some pipes or columns. Pipes and comlumns are once again only really there to liven things up. You should know how to do this, just make a square brush, then go to curve>cylinder. Pipes just look good anywhere, but make sure they go from point a to point b, and dont just stop in the middle.
As for comlumns, i mean like roman columns or something like that, ya know the big marble things. Columns would look good in your map, and would help to add places to hide, like in your alien base room it would work well.
Aslo when doing pipes or columns, if the texture stretches, and becomes blurred, highlight the cylinder, press S, then in surface inspector, click natural.
hope it helps

keep on mapping, and ignore cactus.