Group the instruments into families. On your staff paper, start with the piccolos, flutes, clarinets and oboes at the top of the score. Follow this with the saxophones from highest to lowest: alto, tenor and baritone sax. Then, add the brass starting with trumpets, horns, trombones, baritones and tuba. Follow that with auxiliary percussion, such as bass drums, snare drums, glockenspiels, quads and cymbals.
Determine the pitch range of the melody and decide what sound you want. If you want a subdued, sweet sound, write the part for the woodwinds. If you want a strong brassy sound, give it to the brass instruments. Choose instruments that will be able to play in the middle of the range and still provide the right pitches for the melody. For instance, don't give a melody that occurs above the treble clef staff to a trumpet player, it will be too high.
Listen to the piece you wish to arrange several times. Find the sheet music as well. The sheet music will make it possible to arrange the music more quickly. Otherwise, you will need to sit at a piano and slowly transcribe the music by listening to it a few seconds at a time until you can identify all the notes.
Divide the music into melody, harmony and rhythm. The melody will usually go to the highest instruments, such as the flutes, oboes, clarinets and the trumpets. The harmony will go to the lower-pitched instruments, such as the bassoons, French horns and trombones. The bass note of the harmony will go to the bari saxophone and tubas. Rhythm should be given to the percussion instruments.
Ensure that wind instruments have sufficient places to breathe and rest throughout the music. Breathing every four measures is a good guideline to use.