Mark five staffs on manuscript paper, labelling them from top to bottom: Flute, Oboe, Clarinet, Horn and Bassoon. Begin the flute, oboe, clarinet and horn staffs with treble clefs, the bassoon staff with a bass clef.
Add time and key signatures to each staff. The clarinet line has a key signature one tone below the actual key, e.g., B-flat instead of C. A horn usually has a key signature a fourth above the actual key, e.g., F instead of C.
Write in the melody, dividing it among the instruments according to your own musical taste. In a wind quintet, no instrument dominates the melody, so try to share it equally among the instruments.
Write in the harmonies, keeping the notes sufficiently spaced to allow each voice to sing through clearly. Composer Zeke Hecker advises writing chords in open position, which means having each instrument a fifth or more apart. The harmony rhythm does not have to follow that of the melody.
Write in rests every few bars (measures) for each instrument, as players need to breathe. Resist the temptation to write for all the instruments all of the time. Having just two or three instruments in some passages can add to the texture.
Test your arrangement with a group of players, paying particular attention to the volume of the melody and harmonies. Swap notes between instruments, or move notes up or down an octave to test how the distribution of notes changes the volume and balance.