If you are following all of the above suggestions and are still having a problem, try a tripod to reduce movement in low light. Speaking of light, the more light, the better unless it is behind the subject or throwing distracting shadows. Assuming you are using the camera correctly, these two things will fix a lot of problems. It is very hard to make up for poor light even with all the technology that you can throw at the picture. Believe me, I know, I have taken a lot of bad pictures when I didn't properly consider the light.
Mark E.