Composition and content are vital for sky shots.
Sometimes the shape of the cloud formations you see can make a photo on its own. There are even websites dedicated to photos of unusually shaped clouds. There are no right and wrong answers, use your imagination. Here are some very effective examples from You Connect members.
Blue sky, © Ines Balsiger 2011, Canon IXUS 105
Autumn, © Alec Schaerer 2011, Canon PowerShot A1200
September, © Bo Madsen 2011, Canon PowerShot G6