So it will be kinda like the space battles in UT2004? http://www.youtube.com/watch?v=KpVTvQMz3Bo
Don't forget to put something like a planet, a massive spaceship, asteroids or similar in your levels so it will be easier to navigate and get a sense of direction and perhaps even more importantly a sense of speed (think about the death star scene in Starwars

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Also try avoid making every spaceship battle just about flying out into empty space, reverse and holding your aim and shooting at the a target until it's destroyed, that gets boring quite fast and is probably one of the main reasons why many spaceship shooters never get very popular. Try instead to make it a lot more fast paced so it will be harder aim/lock onto and hit targets but once you do hit you deal a lot of damage, like the railgun in quake or like in that gay erotic volleyball movie Topgun

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When I think about it you should probably don't have too much empty space in your levels at all because as I said that often gets boring and sometimes confusing when you have nothing around you telling you how fast you are going and so on. A battle in an asteroid belt, near the surface of a moon with valleys and mountains, in a space-storm/anomaly or inside a huge space station or even some kind of combination of all that can on the other hand be quite damn awesome if done right

. Just remember go easy on the bloom, blur and lens flare effects, don't use too much brown/grey/black colors on the spaceships and/or on the environments and well simply don't put anything that makes it unnecessary hard to fly around and to navigate in a level.
And for fuck sake if you really are interested and serious about making a cool, unique and fast paced spaceship-shooter then make it first and foremost for PC without any damn unnecessary restrictions! Don't sit around and think to yourself "-but will this work on consoles if we later want to make a port". That's often a formula for an instant, shallow, boring crap title we all seen too often and a game like that will probably just fail unless you guys have 100 million dollars to put on marketing.
Lastly don't forget about making the game fun and entertaining, if you think about levelup crap, perks or similar nonessential bullshit before perfecting the gameplay, levels, graphics, netcode etc your game will probably suck ass. Good luck and have fun!