I have always thought that one of the best ways to improve your skills in Art is to copy the work of others. I completely disagree with anyone who says that such a thing is cheating. Doing a master copy will put you in their shoes, for a moment, will help you think about exactly what it was that the master achieved and how they may have gone about it. It will certainly give you a new and deeper appreciation of the work.
At the moment, in my own work, I have been trying to create more engaging compositions. To make my own compositions better I have been working from masterpieces from some of my artistic heroes and made a small change to each image, just to try and make them my own in some small way.