There are two ways to arrange music, regardless the style:
A) Inventing your own version with the usage of a given phrase or melody. The harmony, form and texture are to be made by youself, giving you much artistic licence.
B) Transribing a piece for another instrumention, keeping the harmony, texture and form close to the original. This is the common way of arranging classical music. You don’t have to invent anything new, but to retrace the process of the composition.
Whether you choose A), B) or a hybrid form, some principles apply either way.
Therefore, here are a few short tips:
1. pay extra attention to the bass line
As the word implies, the bass is the fundament and the most important part of your music. It pays to invest a lot of work here, since a weak bass line will come back at you immediately
2. be minimalistic
That means, for instance: choose one accompanyist figure and stick to it consequently for the whole piece or section.
Prefer simple solutions. also see: 4.
3. proper use of the instruments
You cannot know all your instruments equally well, but it’s important to get acquainted to their range, their tonal characteristics and their nature to make them sound well. Write within the basic range of any instrument for the greater part of the piece. Save special techniques, difficulties and extreme tone ranges for particular moments, like musical climaxes.
4. don’t put in too much at once
Using too many ideas, effects etc. in a short space won’t impress your audience and can appear rather amateur-like. Sadly, this is done even by professional composers. Less is more at this point.
5. listen and rehear frequently
Either let your computer replay or try on your piano what you have written down again and again. Do so after a pause, a coffee-break or the next day. Prefer solutions that don’t become anoying even if you hear them for the 20th time.
6. thoroughness comes first
That’s self-explanatory, fast work alone is worthless.
7. maximise rests
Give every musician time to breathe, to rest, to turn pages etc.
Write as much rests as possible, reduce notes sensibly.
8. grant every instrument its importance
To write the melodic line into only one part is dull for the audience and for the musicians as well. Every player should get important passages for their motivation and fun.
9. drink coffee
Arranging without coffee may be possible, but it’s time-wastingly pointless.
10. use poper texture and engraving
Remember your lessons of the musical texture. You don’t always have to follow them strictly, but they give you a good basis for a balanced and agreeable sound.
Also try to notate or engrave the music with the most possible quality. The appearance of the sheet music is not to be underated regarding the result of the performance (read again: 10 Tips for working with music notation software).
11. choose wisely
The choice of the original source makes up to 50% of a good arrangement. There is music that fits perfectly for some instrumentations, whereas other instrumentations don’t make much sense. Consider the ratio of effort versus outcome. What is doable isn’t necessarily good. It’s perceive and accept; there is enough rubbish out there already!
Looking for ideas for a new piece? Perhaps these wrongly forgotten composers will give you some useful suggestions.