When the strings are more in the background, there are many ways in which they can add interest to the track without becoming too dominant.
The use of a repetitive arpeggiated accompaniment is one such technique – what this means is that the string section can oscillate between the various notes of the arpeggio (for example if the chord is in G major, the first violins could play G,B and D in rapid succession), then the second violins and violas could simultaneously add moving parts, using the other two notes of the same chord. The cello often adds stability to the other parts, by providing a more static line.
These arpeggios can be slurred, played with seperate bows or staccato bowing, they can be quavers or semi-quavers and you can vary the patterns of them according to the context of the track. Arpeggios can be very simple, even alternating between just two notes (rather like the piano accompaniment in the song ‘Imagine’ by John Lennon), but they can also be quite elaborate – using notes of more than one octave.
As the chords change in a song, the arpeggios can simply remain in the same pattern but just progress to the next chord.
Using arpeggios in a string arrangement can add life and movement to the track while remaining quite subtle and they can ‘lift’ a song, giving it buoyancy.