Use sustained notes that slowly change harmony underneath
Layer close intervals like minor seconds and major sevenths
Build with rising melodic lines
Use repeated ostinatos with slight variations
Add dissonant appoggiaturas and suspensions
Increase dynamics gradually
Move from sparse texture to dense texture
Use tremolo for instability
Use sul ponticello for a glassy, tense tone
Use pizzicato for nervous rhythmic energy
Shift between major and minor tonal centers
Delay harmonic resolution
Use chromatic motion in inner voices
Stack chords in low registers for heaviness
Use sudden accents and syncopation
Keep a pedal tone while harmonies change above it
Use string harmonics for eerie tension
Alternate between legato and staccato articulation
Introduce counter-melodies that clash rhythmically
End phrases on unresolved notes