There are many, many ways to get gamification wrong, but there is one that really sticks out head and shoulders above the rest.
The best way to get Gamification wrong is to ask the question “What game mechanics should we include?” before any other questions. Questions like: what is the purpose of this? What is the content? Why are we gamifying? What are we gamifying? Who are we doing it for?
There is nothing wrong with having a list of mechanics that you would like, but it should not be your fist consideration when you are looking at gamification!