Don't think on the single one thing it's possible to get far in different lucid dreaming skills, so i have to select a few.
Confidence i think is really important for starting out as well as for dream control, considering how dream control works.
Dedication is important for general practice, to become better at lucid dreaming.
And imagination is very important for creative dream control as well as for general quality of lucid dreams, especially when aiming for things that are not possible IWL.
Other things mentioned are also important in ways, but those three are most important in my opinion.