One of the most important things to get right when arranging strings for a pop track (or even rock or folk) track is having the insight into how much or little to add and whether the ‘weight’ of the strings is appropriate to the qualities inherent in the track.
Real strings should enhance, enrich and embellish a song, without dominating or being so fancy that the ear is drawn to them and away from the vocal line / other instrumentation. Sometimes writing less does add more and occasionally a sparse string timbre can be ideal to bring out the textures of a more subtle song – a bit like applying a hint of natural looking makeup rather than thick black eyeliner!
Occasionally a client will envisage a huge symphonic string orchestra sound that could be full in it’s own right but in the final mix could be moved back so that it sounds more distant while retaining the orchestral feel. A good example of this would be a powerful rock song or anything that already has lots of other instruments in it and can literally take the weight of a big string section. A string arranger has to think rather like an architect – if strings are applied too heavily onto a delicate song, then the overall structure of the piece can buckle.
In a lighter track, where the strings are going to be quite forward in the mix, they should weave between the vocal lines, rather than doing something elaborate at the same time as the vocal melody. Any intricate writing could occur between verses to add variety and life to the track and if chords are written, the spacings need to allow the melody line to breath. As an example, using lower chords or solo cello / viola parts can compliment a higher or female voice whereas a lighter, higher chord in the violins can frame lower melodic lines or give more of a shimmering effect over a track.