When aiming for the perfect shot, remember to keep sunlight in mind. Too little and you can't see the subject. Too much and one of two things happen. The first is that too much sunlight is directed into the camera's lens or on the subject and washes out the picture. The second is the person being photographed has to blink or close his eyes because of the massive amounts of sunlight coming into his eyes.
When composing your picture, pay attention to the weather. If it is overcast outside, try to keep the sky out of your picture as much as possible. Black and white pictures are also a good choice if you want to shoot outside on an overcast day. If the weather is nice and sunny, you will get a lot of great pictures, just make sure your subject isn't squinting at the sun.
Make use of the instant feedback you get from a digital camera. The screen on your digital camera can show you the basics of how your photo came out the instant you snap the shot. Learn from your mistakes and take another shot, there's no need to wait for your prints anymore.
I am selling a print. This video serves as a blatant sales pitch, but I also like to think that this video can help others who are thinking about selling their work.