Hi Jaime
For my GCSE integrated assignment, i had to produce a film score for a western, and picked up a few tips for film music:
1. If you are trying to make it sound expansive, sythesized strings on a keyboard is a good instrument to use, and have a continuous note in the bass, e.g. in G major, a low G and then the octave below,simultaneously.
2. If you want an increase in activity, could use a crescendo, or vice versa for decrease in activity in the scene.
3. For any kind of transport, a bass line which starts slowly, then gradually speeds up, but with a moving melody, e.g. flute or violin.
4. If you want a peaceful sounding beginning try having flute trills, e.g. a nice sounding one is a high C done with a trill key.
Hope some of these help.
If i get any more ideas, i'll let u know.
Helen