Fast shutter speed, steady hand, clear lens, stationary subject.
(Your camera should indicate auto focus lock with either a green light or a beep and it should be exposed correctly)
With those four things, if your photos still aren't crisp and clear, you might have a dirty sensor or a bad camera.
Where do you live? I can find you an authorized repair center in your city or I can go to
and fill out the online repair form and they will give you all the info you need to get it fixed.