Harmonizing chords using the strict rules of chorale writing (SATB) is a time-honored way to get started with harmony. I'd be happy to help you, just call me.
1. Spacing between SA and AT cannot exceed an octave
2. Range of SATB should be reviewed before starting.
3. Double the root, but never in consecutive voices.
4. No voice crossing within a measure.
5. All chords must have a 3rd.
6. Common tones repeat, most of the time.
Computer realization of the exercises.
You've got to learn your instrument. Then, you practice, practice, practice. And then, when you finally get up there on the bandstand, forget all that and just wail.
I'm a professional pianist and music educator in West Toronto Ontario. I'm also a devoted percussionist and drum teacher.