The truth.
You can't change your history. Having two jobs for 12 years each may well be seen as preferable to someone who changes jobs every year.
A good CV is vital, especially if your potential employer doesn't know you from Adam, or Eve. Having sifted through many a CV over the years, you have to make yours stand out from the others. Clear presentation, good use of English, and for me the avoidance of bull**** are all a good start.
Some employers now use templates for you to complete, rather than accept a free format CV. Read the question carefully and answer the question you were asked, you'll be surprised how many don't.