You did not say what kind of lighting gear you have. You do not need a lot of expensive lighting gear, but you must have some lamps separate from the camera, with some diffusers or reflectors for softer effects (can be made from cheap stuff like a disposable translucent plastic table cloth and white card stock), flags (light blockers) - pieces of cardboard will do, and some clips/clothes pins to hold stuff in place. Doesn't matter if it looks absolutely ratty, it is not in the picture.
First consideration is the setup and lighting. If it doesn't look good to your eye, it won't look good to the camera. Experiment, and be deliberate about the perspective you want. Choose your main light direction, size/distance (hardness/softness) to bring out form and texture. Do not worry about exposure at this point. You will adjust it in the camera. Add a little fill light if the shadows are too dark.
Only then worry about the camera settings to capture the image that you set the lights for, with the desired depth of field.
Worry about exposure last. Do not use automatic settings except as a quick way to determine exposure. The subject isn't going anywhere, so use a tripod and manual camera settings with as small an aperture and slow a shutter as you need, while also using minimum ISO. Still life studio shots often may use shutter settings on the order of one second or longer.
Do any of these hints help?
