Viper, these are looking superb!!!
Now you need to start playing with the ships, adding shadows and altering brightness/contrast to suit their surroundings!
Also for lights check out some of the many Photoshop Lightsabre tutorials on YouTube. Applying some new, complex techniques will also add to your understanding of the software, and will get you moving around some of the more interesting tools.
You are such a great contributor to this forum, I would love to see your skills develop as you have an amazing and inspirational imagination.