Lady Julianne has a great article over at this second's obsession titled How to Avoid Getting Bored With the Way You Dress.
One thing I've emphasized here before is that you should try to develop your own sense of style instead of copying everything you see in fashion magazines. In the words of Lady Julianne:
"Try to develop your own personal touches, your trademarks.I would say that my "trademarks" are the hats or scarves that I wear with my outfits. What about you?
Small things are the best for this, I think. My grandmother loves earrings and has a massive, wonderfully eccentric collection. She has everything from crocodiles to strawberries, and from traffic lights to classic pearls. You could also have an burgeoning obsession with one particular image or group of images, for example, fruit."