Here is a good recommendation for the beginners in Deleuze's thought. It is very important where to begin especially when dealing with a complex thought like Deleuze's. What is important is to understand what he is aiming for all the way. So Nietzsche and Philosophy is the perfect choice to decipher Deleuze's will in philosophy. Although I think that it is pretty hard to have a complete, wholesome idea about his philosophy without considering Bergson's affect on him. The fundamental notion of "difference" in the works of Deleuze forms itself alongside of the evaluation of Bergson's concept of "durée" as the living time. So I would add Bergson readings (not by Deleuze, but by himself, for example Matter and Memory) to Nietzche and Philosophy in order to enable a deeper understanding of the will introduced in Deleuze's works.