Good answer above by Fizz.
Also, consider what other well-studied traits are similar. Here's a long list: http://www.sjdm.org/dmidi/All_Scales.html
It sounds to me like some items from the Big Five could overlap. For example, in these facets (each would have multiple items):
Extraversion: Assertiveness (forceful), Activity (energetic), Excitement-seeking (adventurous)
Conscientiousness: Dutifulness (not careless), Achievement striving (thorough)
and the opposite of this one:
Agreeableness: Modesty (not showing off)
Also see a different taxonomy called the HEXACO, which has a whole trait called Honesty-Humility (presumably, you want to track scored on the Humility part)
hexaco.org/
