If you are having trouble getting started don't fret. There are times when I'm overcome with ideas and the sentences flow from me like water. Other times, writing can be as difficult as golf. During the difficult times I force myself to write a sentence -- a sentence about anything.
"Bobby was a boy who liked polka dots. Red, green or blue -- polka dots were his peculiar passion."
Once I have a sentence down, I can begin to see the many avenues which I can take.