Read The Second Generation first, then move on to Dragons of Summer Flame, which takes place 30 years after the original novels and sets the stage for all of the novels that take place in the Fifth Age.
The next set you should pick up is the Dragons of the New Age series. Even though this was not written by Tracy or Margret, it is a good foundation for what happens in the Fifth Age of Krynn.
Many people do not like Jean Rabe's writing of this series. Matt thought it was ok on the whole: she was given the unpleasant task of introducing the Fifth Age, which many people were not thrilled about in the first place. There were some portions of the story that were unbelieveable, and others portions where the characters did not seem "true", but on the whole a good read.
Finally, along the main 5th Age list of reading we arrive at the latest series by Tracy and Margret. The War of Souls.
Dragons of a Fallen Sun
Dragons of a Lost Star
Dragons of a Vanished Moon (To be published summer 2002)
This is an excellent series, though the twists and turns the series has taken so far are really shocking. Tracy Hickman says that the series will bring the world back together, and (with having had lunch with him!) Matt believes that it will ultimately be really good for the world as a whole. The unexpected plot twists in the interim are gut-wrenching, though.