The craft of arranging is partly comparable to composing. It means the construction of musical lines and melodies that help to shape and/or complement a composition. In a way this process starts already with the basic instrumentation of a musical piece, but most of the time it is more applicable to the additional musical parts. For example in the case of a string quartet adding some more color and body to an acoustic ballad. Or backing vocals accentuating and lifting up a lead vocal part.
Musical arranging is on the one hand a real musical process, where the composer or arranger “hears” or makes up musical lines and motives and then captures them in one way or the other.
In some situations it’s very handy if the arranger knows some musical theory. For instance the range of the relevant instruments, the places where horn players or singers need to breath, or which bow strokes or articulations string players use to enhance their musical expression. It can also be essential that the arranger knows how to read and write musical notation, in case he has to provide sheet music for session players.
A creative artist can have plenty of ideas for arrangements himself. He might “hear” certain parts in his head, but may not know how to materialize or present them. I often advise people to make scrap recordings of their ideas on their telephones, just by humming or playing them provisionally. Later I can help them to transform these ideas into full-fledged parts and arrangements.
Of course I also provide custom made arrangements for every requested instrument or instrumental section, for both domestic and independent productions, in case the client doesn’t really have any ideas, but still wishes a bigger sound.