As a student of gun photography I'll add a few thoughts
Lighting needs to be diffused / indirect. Harsh reflections are ugly! I use a home made light box, sometimes adding light "bounced" off the ceiling. Occasionally I use natural light from a window and very rarely do I shoot outdoors as the bright sun is too intense. Over exposed areas in a digital photo loose all detail and appear as pure white, those areas are "blown out" and the details are just not there in the file. Conversely, areas that appear too dark can often be saved in post processing and the details made visible. So, if anything underexpose a bit - there is a lot of detail hiding in the shadows!
Mount your camera on a tripod and use a remote release to eliminate vibration. This will accomplish a few things that make your photos better. First, shoot at your camera's base (lowest) ISO setting - virtually all digital cameras will capture a "cleaner" image than at higher ISO settings. Second, shoot at a smaller (higher number) f stop. f8 to f11 is good with most DSLR cameras. This will provide a greater depth of field (the depth of the area in sharp focus). For example, if you shoot an N frame revolver from the side, at f2.8 the close edge of the cylinder might be in perfect focus while the frame & barrel are blurry. At f11, all of the gun will be likely to be in focus. This too can be overdone, set your aperture (f stop) too small and the entire image may loose sharpness due to defraction - keep it around f8-f11 with a DSLR. Speaking of focus, autofocus used skillfully will do; manual is better if your camera (an your eyes!) allow it. Shooting from a tripod allows the resulting slow shutter speed (often 2 or more seconds) without picture ruining motion blur.
Set your camera to shoot the largest JPG images it can, or even better RAW files if available. Capture all the detail and information that you can with your camera. Then, use it by getting to know your post processing software - Photoshop, etc. It can provide a multitude of options for making you images look great, and the better the images and more data that you provide, the better the final product will be.
Hope that helps without being too confusing
Here are a couple recent images taken with my D300 and a 30+ year old manual focus lens:
