The one bit of advice I have is not to be afraid to go back to manual. Just because the camera and it's little micro chips can make all the decisions for you doesn't neccesarily mean it should. Yo'ure the photographer and the camera is a tool and you should be making the decisions on how a particular shot should come out.
My best example is trying to shoot macro. The camera has numerous focal points and even if you set it to one it won't focus on anything if you don't frame you subject in the center of the picture. Here's a fine time to turn off the auto focus and do it yourself. This gives you the opportunity to fine tune the focus exactly where you want it on the subject, whether that be the center or some small detail.
I have also played around with the aperture manually and still need to do more with that. My advice, don't be afraid of going back to the good old days of manual setting even on today's high end digital cameras. You may be surprised at the results.