I think it looks quite detailed already.  A really good texture, with some good displacement or normal mapping, will make it appear very complex.  But if you really want to add some more detail to the geometry, then I'd suggest adding some more greeble to the body of the ship.  Most modelling software have plugins or addons, or scripts, which could do this automatically.  Don't know exactly what software you used here, but I know Blender, 3dsmax, Maya, Lightwave, and Cinema4d all have some kind of greeble or nurnies plugin.  That is usually what most people do to quickly create detailed panels, grids, and all kinds of small sci-fi details on a ship.

That top tail fin seems to have good paneling and detail. Maybe do that same kind of modelling on the sides of the ship, and it will add another layer of interest.  In the end, the highest level of realism will come in the textures and materials.  You can get away with less geometry if your textures are outstanding.

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.