1) Learn how to unwrap models properly. This is essential if you want to make really good textures.
Make sure you pay attention to arrangement of the faces, and most importantly, seams, as it will make continous details alot easier to create.
2) Do not, do not tile textures like you did with the plane. If you want to be a good texturer, learn to make custom base textures, and then paint details on top of it.
For vents, grilles and other misc bits of detailing, you can easily find a wealth of them via Google.
3) Weathering. A lot of newbies neglect weathering, resulting in models looking so shiny that they can't possibly have come out of the factories yet, let alone make it to the battlefield.
4) Shadows. In addition to weathering, shadowing adds tremendously to the quality of a texture.
Keep these in mind and you'll be able to texture like this in no time.
