Hi fernandez, I've replied to your question on another site, but I'll post it here as well.
I prefer using Center AF mode to the default Multi AF mode, since I have control over what the camera will focus on. In Multi AF mode, the camera will choose a strongly contrasting subject near the center of the LCD, so even if your subject is a little off center, it will still be in sharp focus. It doesn't always get you the result that you want, though. I prefer to use Center AF mode, half-press the shutter, recompose the shot if necessary, then press all the way to take the picture. Great results just about every time. Just keep in mind that the camera focuses by contrast detection, so you have to point the AF frame at something with strong enough contrast. You can't focus on a blank wall, for example.
That's one suggestion. One person who was having a problem with blurry pictures later found out that he/she was experiencing the problem when the shutter speed was too low. When you half-press the shutter button, the shutter speed is displayed on the LCD. If it is below 1/60s, it might be too slow for you to hand-hold the camera. Camera shake will result in a blurry picture. Even if you think you're very steady handed, sometimes, well, you're not! Small cameras such as this are more difficult to hold still. So you can either use something to steady the camera (like a tripod), increase the ISO until the shutter speed is fast enough, or use your flash.
Hope this helps.