Here are a few reasons why pictures come out blurred.
1. Out of focus. Press the shutter release button half-way first to give the camera ample time to autofocus. If you are using manual focus on a dSLR, calibrate the diopter if you keep getting blurred shots. Consult the manual about it.
2. Movement. Either you or the subject moved. Make sure both you and the subject stay still as the picture is taken. If the camera has anti-shake technology, turn it on. If needed, use a tripod.
2. Slow shutter speed. Long shutter times allow movement to be more evident. Increase shutter speed to go faster.
3. Low light. Basic principles of photography dictate that the lower the amount of light used, the longer the picture has to be taken. You can use a higher ISO setting, a larger aperture size or both to increase shutter speed.
4. Subject is too near. Lenses have a minimum focusing distance. If you are nearer than that, the camera won't be able to focus properly on the subject. Simply step back.
5. Lens is dirty. Classic!
Now you know!