Also remember that with a DSLR and a wide aperture (low f-stop number) you will get a smaller depth of field, so parts of your image may be blurred whilst other parts are focused. Check to see if parts are in focus.
What was your shutter speed and did you use a tripod? You need to hold the camera very steady to get a good shot. That is what i found out using mine and mess with the shutter speed. A good shutter speed for me is 125-200 with ISO at 200 depending on the lighting.
