More Voice-Leading Guidelines
(for the fastidious)
Theory Things   William Wieland
Do not overlap voices.
Avoid augmented or diminished melodic intervals unless a 7th chord or diminished triad is outlined.
Follow large melodic leaps by step in the opposite direction.
Do not approach a chordal seventh by a descending leap.
Do not approach perfect harmonic intervals by parallel or similar motion. Two exceptions:
    Perfect Fourths
    Horn Fifths
Do not write perfect parallel unisons, fifths or octaves from downbeat to downbeat.
Do not write succesive perfect unisons, fifths or octaves in contrary motion.
Resolve tritones properly. (The A4 resolves to a 6th and the d5 resolves to a 3rd.)
Resolve altered pitches by ½ step in the direction of their alteration.
Double the bass of root position and 2nd inversion triads. 1st inversion has no rigid doubling rule.
If you thirst for more rules, sample these counterpoint books.