Start by being honest to yourself. It is said that best assessment is self assessment. Judge yourself whether you're being honest or not.
"The foundation stones for a balanced success are honesty, character, integrity, faith, love and loyalty."
--Zig Ziglar--
"Honesty is the best policy"
--Benjamin Franklin--
Honesty is the quality of being fair and truthful. If something you do is breaking the law or you have to hide it because you'll get in trouble, you are probably not being honest.
Many people understand the definition of honesty to be "don't lie". But the complete definition of honesty also means that an honest person doesn't do things that are morally wrong.
This part of the definition of honesty includes not hiding the truth (deceiving), not breaking rules to gain an advantage (cheating), and not taking something that isn't yours (stealing) and any other action that you would hide because it is against what you consider morally right.
References:
1. http://talkingtreebooks.com/what_is_onesty.html
2. Google Images