Sales & Development “guru” Paul J. Meyer wrote a book (many books, actually) called “Attitude is Everything.” What may become his legacy to the world of goal setting, was an acronym within this book: SMART goals.

SMART goals are
Specific
Measureable
Attainable
Realistic
Timely

[side note: there have been some variations on what the acronym stands for, which are included on Project Smart's (what a great name!) site.]

Googling “SMART goals” will turn up oodles of sites referencing this memorable, simple to use tool for goal setting. TopAchievement.com provides a wonderfully explicit explanation which you can read here.

You can also use mind mapping with this method to break down a challenging goal.