How much of your own experience is reflected in your stories? Terri Henson, Manchester

I always want that the readers (of my books) and the viewers (of the films based on my screenplays) to feel that my work has "street" - authenticity and honesty. I want to know that the viewers and readers can say: "He was there and he knows what he is talking about."

So yes, my own experience is reflected in my stories, but my imagination is too. Imagination is the personal experience transformed into something else.

I'm an English student who wants to pursue a career as a screenwriter. Can you tell me how you started out? Do you have any tips for people in my position? Carly Halliwell, Southampton

I started out as a novelist. Soon after my novels were published, some film producers contacted me to buy the rights for cinema. Then I began writing screenplays.

But I must tell you I have produced, directed, written and edited for television and radio, so I was acquainted with working with sound and images.

My advice is simple: write, write, write. There is nothing more powerful in the film industry that to have something to show, a piece of work that represents what you are and where you are going.

And my second piece of advice: end what you begin writing.

Both of your films that I've seen - Amores Perros and 21 Grams - are about death and tragedy. Have you ever considered writing on lighter subjects? Callie Stanford, Chesterfield

My first novel Guillotine Squad, was a dark comedy. I directed and wrote a short film, Rogelio, which again, was a dark comedy. My screenplay, Slow Fire, is a comedy about people going to see a house on fire.

Did you have any actors in mind to play the characters when you were writing the screenplay? Since Naomi Watts was not as well known as Sean Penn, what drew you and the director to her? Alice Greenblatt, Freehold, USA

I wrote the screenplay without any actors in mind to play the parts. The choice of Naomi was completely the decision of the director. He choose her for her tremendous range of emotions and her great talent.

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