Identify in the score with a pencil the necessary chords and harmony that support the melody. Chord markings sometimes appear above the melody line in block letters, with capital for major chords and lower-case for minor chords. Sometimes, you must read the notes to determine the chords. See "Tips" for information on chord identification.
Choose which chords and inversions of chords you wish to use to support the melody and indicate them in the score.
Make a baseline to be played by the pedals of the organ, using the information about the chords you gathered in Steps 1 and 2. Remember to use inversions of some chords so the baseline is not unnecessarily awkward.
Make some choices about how to vary one verse from the preceding and following. Variation in music makes it more interesting to hear. Some possible changes might be difference in stops (organ sounds) used, difference in registers (high versus low), and playing louder or softer.
Consider adding a short musical introduction or interludes between verses for more musical variation.
Follow Steps 1 and 2 in Section 1 for identifying and marking chords, just as with a pipe organ.
Write bass-lines for electric organs or organs without pedals in the lowest played music on the keyboard. The left hand of the organ player usually takes this part.
Experiment as you arrange the tune. Electric organs may require different chord voicings (constructions of chords) than pipe organs in order to sound right. Due to the wide variety of organs and music, use your ear to determine what sounds full and musical.