It is not the camera, it is the lighting. I shoot everything full manual. How well a photo turns out is directly proportional to how long it takes to setup the lighting. If I use flash, it takes at least three hours of setup to get a magazine quality photo. Most of the time, I just let myself be satisfied with what I get from my iPhone.
Outside on an overcast day against a simple, light colored background is the quickest and easiest way to get a good photo, even if not the most convenient in terms of timing. A large diffuser like a white sheet or clear shower curtain, can turn a sunny day into an overcast day. Also, Northern, or other indirect light through an open garage door or a large picture window, also works wonders.
Like I said, it is all about the light. You can use various things to reflect light where you want it and diffuse it when hitting your subject. White poster board and aluminum foil work as well as anything to reflect light. I will also use white ceilings and walls to diffuse and redirect light. A single flash unit reflected off a ceiling or wall can provide quite good light in some places. You have to play with the light very much like you play pool.
The next thing you must be aware of is the white balance or the temperature(color) of the light you are using to illuminate your subject. You must tell your camera the temperature of the light you are using so that it can assign the correct color values. This is the White Balance and most cameras have a setting for this. Usually, it is in terms of Sunny, Cloudy, Shade, Flash, Tungsten, or Fluorescent. Usually, Sunny, Cloudy, Flash, or Tungsten cover it. The temperature of Cloudy and Flash are very close to each other. In the film days, you picked a film to match the temperature of the light you were using. With digital cameras, you set the white balance.
The same goes for the ISO. However, for subjects that don't move, you use ISO 100 and a tripod or other stand for your camera. You then set the exposure for how ever long the light meter tells you. I routinely shoots exposures of several seconds doing the interior of a building. If what you are photographing doesn't move, it doesn't matter about the exposure time. The aperture is the best for your subject and desired depth of field. I have found that f/16 is best for guns and such that you photograph close. F/11 generally gives the best detail and depth of field for photographing large areas. Portraits are usually done with the largest aperture your lens will handle so that only the eyes are sharp and everything else is slightly out of focus, the background being completely blurred.
As the preceding should have hinted at, it is knowledge that makes a good photograph, not the camera. This is a continual sore point with professional photographers. The general public seems to think an expensive camera is what produces a good photograph. The most expensive cameras, like say an Hasselblad, have very few advanced (microprocessor based) features as they are almost always used full manual. Cameras designed for professional use are usually simpler, requiring more input from the photographer, and assuming significant post processing. Pros really prefer simple cameras. If I could afford it, I would use a little Leica as my personal camera. They cost upwards of $10K, are about the size of and thickness of two iPhones , and have very few features aside from autofocus.
So, don't buy a new camera; buy this book; Light Science and Magic: An introduction to photographic lighting
http://www.amazon.com/Light-Science-Magic-Introduction-Photographic/dp/0240812255.
