Plot on rails: Too often amateur writing sets up what the protagonist has to accomplish at the beginning of the story and sticks to that right to the end. That may work for some shorts, but in a novel you want events to move the goalposts. It allows the character to discover what she or the world really needs, rather than what was thought at the beginning. Remember, Frodo didn’t set out from Bag End thinking he’d have to go to Mount Doom, he was just trying to get the ring out of the Shire and meet Gandalf. A story is not a baseball game, objectives and rewards can change with the character and situation. Go watch Run Lola Run if you don’t believe me.