This is a long one, but then, you did ask. . . .

I take a couple of slightly different approaches, depending on the source of the song. If I'm learning it from a record (or tape or CD, etc.), I listen to it several times, humming or singing along with it. While I'm doing this, I'm writing down the words. I used to do it longhand, but now I generally type them out on my laptop (e.g., listening to the CD in the CD drive while typing and playing it several times if necessary, which it usually is). By the time I've got the words all typed, the tune is usually fairly well established in my ear.

I'll try singing the song, reading the words off the screen. I may print off a copy of the words and stick it into a shirt pocket, so that, as I wander about singing the song (at least in my head), if I get stuck, I can pull it out and refresh my memory.
As I'm memorizing the words and tune, I'll pick up the guitar and play through the melody, to determine the highest and lowest notes in the song, and that gives me a clue as to what key would work best for my voice. As I do this, chords tend to suggest themselves, but I save that till later. I put the guitar aside for now.

If I'm learning a song from a song book, I play through the melody on the guitar (I can sight-read for voice, but I'm lousy at it, and the first time through is usually a laborious process—easier for me to pick it out on the guitar). Reading the words and picking out the melody on the guitar, I try singing through the song until I've got the tune in my ear. By this time, I've undoubtedly learned that the tune, as written, is too high for my voice (I'm a bass-baritone, and most song books put songs in a sort of average or mid-range key. Too high for me). Here again, I check the highest and lowest notes written, and crank them down to a range that's more compatible. But still, I don't work out the chords and the rest of the accompaniment yet. Once again, I set the guitar aside. [There is a good reason for this.] Then I print off a copy of the words to carry around with me, as above (crib sheet).

Then, whether from a recording or a song book, I sing the song a lot—without accompaniment—without the guitar, until I have it down pat. I carry a Kratt "Master Key" chromatic pitch pipe (a little black and chrome "circular harmonica") in my pocket along with the words, and I check from time to time to see just where I am as I practice the song. Still, no guitar.

I study the song to make sure that I know what the heck it's all about. This seems obvious, but I've noticed that a lot of singers do the same thing I used to do when I first started out:   learn a song without really knowing what it was all about and sing it by rote. Then I took some singing lessons from a teacher who, when I sang songs for him that I was learning, would stop me and say, 'Okay, what does that line mean?" He knew perfectly well, but he wanted to make sure that I knew what the blazes I was singing about, and not just singing "words." Good point! Then, I work out phrasing and breathing points to try to bring out the meaning of the words. It's at this point that I may "folk process" a bit. Without changing the sense of a line, I may change a word or two, or the order or words, if a line sings clumsily. I try not to change the tune any, and almost never do, unless an interval is just bloody awkward. In that case, I'll try to pick a note that harmonizes with the "original" note. If well chosen, most people won't even notice, and if I'm singing with someone who's singing the "right" tune, at least we won't "clank." This sort of thing, I was told by an English professor who taught a course I took in "The Popular Ballad," is permissible if done judiciously and with understanding:   "A minstrel's prerogative."

When memorizing a song, I will often sing through the song silently, in my head, as I'm going to sleep. Experience tells me that this works well to speed the process. If you've listened to the song a lot, it's in there, even if you can't get at it all at once. Let your subconscious work on it some.

Once I've got the song down solidly, I sing it without accompany for several days or a week or two. Then I pick up the guitar. By now, my voice has pretty well established what key I should sing the song in.

This is important. Some keys on the guitar, particularly those using first-position open-string chords, are fairly easy to play in. C, G, D, A, and E, along with Am, Em, and sometimes Dm, depending. Do not let the ease or the difficulty of playing in a particular key induce you or force you to sing in a key that's not optimum for your voice. If you find that you've been singing the song (unaccompanied) in the key of B (not easy to play on the guitar), you may be perfectly comfortable upping it a half-step to C. Or in F, you might get away with dropping it a half-step to E. But especially in minor keys, or in major keys where you want to use some of the relative minor chords, the guitar can be pretty limited.

Or you may find that you're singing it in D or E, but you can get a much better accompaniment (along with a couple of relative minor chords thrown in) in the key of C.

Use a capo.

The accompaniment must be in the service of, and subservient to, the song. Not the other way around.

One of the advantages of all that practice singing without accompaniment is that if you want to sing somewhere and you don't have an instrument available, you're still in good shape, because you're not dependent on the instrument. And singing unaccompanied is very "traditional." (Some singers come all unglued if they don't have a guitar to hide behind.)

By the way, one of the advantages of typing out the words on the computer is that when you've worked out what key you're going to do the song in and know the chords, you can pull up the words, double-space the first verse and chorus, and type the chords in over the words where the changes occur. Then, format the song-sheet nicely, add the title at the top in a larger font and boldface [I usually type something like "(traditional – Child #20)" in italics under the title], then at the bottom (or on another page for the back of the sheet), I add notes about where I learned the song and some background about the song itself. Save it to disk, of course. Then print it out on a good piece of 24 lb. bond paper, punch it with a three-hole punch, and put it into a three-ring binder.

Bingo!

Don Firth