Tips?
You look well underway already. "You don' neeed no stinkin' tips!"
The ship looks good so far.
I would consider looking into some casting materials.
So when you build a turret, you can get it perfect and then cover it silicone rubber, and create a mold so that you can duplicate it without building every one and every detail individually.
The same goes for doors and hatches and other details that will be required in multiple instances.
Molding would also allow you to scavange parts from other models of the same scale, and use those details on your project.
Keep us up to date on the progress.
[edit]
Plastruct.com may offer some 1/200 scale "architectural" figures.
Also, N or Z scale railroad figures may be usable.