Write music in minor keys. It also is possible to use other scale possibilities, such as the octatonic scale, which alternates between half steps and whole steps.
Achieve a creepy sound using augmented triads throughout the composition. Augmented triads build upon major thirds and have a dissonant quality to them.
Interchange high-pitched fragments in the piano or strings to create a sense of impending doom. Avoid writing complete melodies and break the music up into smaller motivic elements that help keep the piece moving forward.
Include electronic elements in the score. Electronic music is becoming much more widely accepted and used; manipulate everyday sounds in a program that allows musical editing. Some unique sounds become possible by using everyday objects as mundane as a set of keys.
Write violin harmonics into the score. These harmonics create a shimmering, high-pitched element that can be great for adding suspense. Take advantage of the many techniques available on each instrument.
Write col legno for the violin. This technique involves using the back of the violin bow to perform the notated pitches. The effect is a wooden, clattering sound that may mimic the sound of "dancing bones."
Study privately with a composer online or in person to improve writing ability. If you are interested in writing more complex and sophisticated music, this is the way to go.