To choose your word, envision the person that, ideally, you want to be. Then, pick your word based on that person and their characteristics, not on past mistakes, failures, or insufficiencies.
As for me... last year I chose the word Give. This year... well, I haven't yet decided on a word. I have several I am considering. Believe me, it is a LOT harder than you can imagine! When there are so many things you desire for your life, it is hard to narrow down to just one word. And yet, that is the whole idea - focusing on one area to grow in, in your relationship with God and others, and in your own personal life and desires and dreams.
I encourage you to log onto My One Word, for more information, help picking your word, and stories of people that have been impacted by this revolutionary idea.