When taking close up shots,it is generally necessary to have a tripod,or other steady,to avoid camera shake.Even just holding the camera down on a flat surface will help.The short focus magnifies any movement to the point where your photos become blurry.Also,with digi-cameras,the shutter button usually has 2 distinct "phases",very light pressure will focus,and full depression takes the shot.On my camera at least,I need to hold the 1st position for a second or so,to give it time to focus properly.This may not be necessary with the more expensive cameras though.
I also switch off flash for all close up shots.If they come out too dark,you can always lighten the photo with your camera software.
I have taken shots from as little as 3" away with this setup,and they look ok.Be aware though,that your depth of field becomes an issue with any close up photography.
Hans.