i think you got the spirit for this but lack the experiance which is natural.

several tip:
1: add a spawn point so we can see its relative size.
2: use less lage brushes and more small(so it seems less blocky).
3: dont use monothone texture like the grey/white one.
4: use muliple layers.
5: future idee is to add light map and shot screens out of a debugger

do up some idee out of these:
http://www.ed.nl/multimedia/archive/...rt_706989b.jpg
http://www.airport-hotels.tk/wp-cont...-airport-1.jpg (for how they are connected)

i hope this will help you out for now and motivates you to do more mapping.
for mroe experd constructive critism youve got to wait for slugheady/hellsnipe/StephanM.

greetings SilentSoul.