You might wanna distance yourself from the stargate SG1 series a little more...
http ://
www.thescifiworld.net/img/wallpapers/st ... 24x768.jpg
All those big numbers seem a little out of place, it looks like you've modelled the numbers on rather than textured them on as you should do (people paint numbers and letters onto ships and tanks and airliners, they dont get metal stencils and paint them black/white), they're simply too obvious and it doesn't come off well, and them all being different colours they clash.
And your lighting and windows and weapons fire look more like sprites. Perhaps if you decided on a single colour scheme such as bright white and pale blues, then tied that in with the background scenery for an overall colour scheme for highlighted objects, like a blue planet and blue sun...
And the metallic texture you've used across the entire thing in most places, it looks busy and complicated rather than detailed.... There needs to be a little more variation in colour else it'll just look the same throughout... Maybe if you had larger pieces like 'hull plating'.
And you need to make the insides of your cannons darker than the outside.
You might want a background to fit with your colour scheme should you have one.
http ://67.15.36.49/articles/Space/images/hameed_nawaz_pic2.jpg
http ://67.15.36.49/articles/Space/images/gary_tonge_pic1.jpg
You dont need to use a star scape a sun and a set of planets awkwardly close to each other to make a space scene.