Can I shift away from an enemy and then use a move action to get farther away from them without provoking an attack of opportunity?
Yes, if at the end of the shift you are not on a threatened square.
Shift is a move action that lets you move 1 square without provoking opportunity attacks. You can then convert your standard action to a move action in order to walk away your speed.
Note that some creatures may have a reach of 2 squares or more with their basic attacks. These creatures still threaten only adjacent squares unless they also have the Threatening Reach trait.