rules for assigning chords to melody notes based on degrees of scale

[timothy42b]

I know this question is so basic I'm a bit embarassed to ask it.

But given a simple melody, how do I quickly add guitar chords for a praise and worship group?  (and how do I explain what I do?) (or piano chords, doesn't matter)

I know I have seen a web site that listed degrees of the scale, chord choices for each one, and rules for choosing which one, but I couldn't find it again.  It mentioned chord tones and tension tones. 

I actually have done this quite a few times, by sticking to I, IV, and V7, and with trial and error could eventually get something simple that worked.  But I know there are some rules out there somewhere. 

Thanks,
Tim

[gerryjay]

 i believe there are two complementary ways to face it.

 one is to study written harmony in-depth, memorize the spell of chords, their relationships, analyses and so on. a teacher is mostly welcome.
 another is to improvise. start with I IV V7 (as you said). then add the relatives; then secondary dominants; and so on.

 about what goes with what, it's difficult to tell because it's not that simple. let's say that you have three notes in a major: c sharp - d - e. the alternatives are almost endless. if you want to harmonize each note with a chord, then you have the following:
 c sharp: C#m (as fundamental), A (as third), F#m (as fifth), Dmaj7 (as seventh), etc;
 d: D, Bm, G#o, E7;
 e: E or E7, C#m, A, F#m7.
 those within the boundaries of simple diatonicism. it's not unlikely to find the d harmonized with a Bb7. however, here comes the limitation of harmonic field. if you are working only with I IV V7, you would have only two chords to each note, and furthermore, two main possibilites (A D E7, or Dmaj7 E7 A. in the latter there is an apparent mistake about the tritone).
 anyway, you can prefere harmonize two notes with a single chord, or the three with the same: it's about your ear and the style you're in.

 remind that a fluent knowledge of harmony and harmonization is a work of years.

 hope that helps a bit.
 

[danny elfboy]

Arranging, harmozing or composing music is not done by strict rules.
In other words it's not like each degree of a scale accepts just one kind of chord.

Yeah there are rules about what goes with what, but those roles admit hundreds of possibilities and eventually it's all about your ear and what you like.

For each working harmonizaton and arrangement there are thousands of different working possibilities still using chords and patterns that go well with them.

The melody of course follows no rulesand it's just your and someone's else ruleless creation but even the accompainment is not just rule based. 90% of it is based on what sounds good to your ear obtained through improvization, intuition or just trying.

[timothy42b]

I know there's more to it than rules but I have guitar players who range from beginners to, well, beginners.

As a first cut, I'll use I for scale degrees 1,3,5; V7 for 2,4,5,7, and IV for 6 and strong 4.  And try to always end with V-I or IV-I.

Can you suggest substitutions for some chords, for times when I have a better guitar player or I'm on keyboard?  Or a website that has a good description.