Yesterday I covered matching pitch for beginning singers. Once you've mastered singing a melody in tune, you'll find yourself wanting to sing harmony!
Sometimes trying to harmonize feels like trying to climb up a slope where you keep sliding back down despite repeated attempts. What follows are some tips that will hopefully help you gain some traction.
1. Put on some music and start experimenting with your voice. Harmony is, essentially, multiple pitches at once. One way to proceed is to put on a favorite song (alone in the car?) and start singing whatever comes to you. Try some high notes, low notes, long tones, short tones. By definition if you are not singing the melody (i.e., the tune) you are singing harmony, no matter how terrible it may sound. Just call it avant garde. As I tell the Intown Women's Glee Club, whatever you sing will either sound good or...interesting. There is Good Interesting and Interesting Interesting, but isn't that in the ear of the beholder?
2. If you are having trouble breaking away from the melody, drop the words. Listen to the Beatles' "Hey Jude" (I know, what a chore). During the first verse, it's just Paul singing alone. In the second verse, on the word "minute," the other guys come in singing "ahhhhh." Think about how much easier it is to just pick a note and stick with it, rather than come up with a distinct harmony line! Still, it's completely legit. You can add aaahs and la la las to just about anything.
3. Don't know what notes to sing? Try the Electric Fence method. If you're on the fence between good and interesting, make it an electric fence and you'll hop right to the good side!
If you sing out nice and strong, you will find that some pitches give you a pleasant buzzing vibration as the frequencies bounce off each other (no, I'm not a physicist, why do you ask?).
On the other hand, some notes that you sing will make you recoil. They just don't sound right or feel good, so you get off right away. Over time you will condition yourself to steer clear of the zaps and stick to the notes that sound good, just like the obedient little goat at my grandparents' farm (it wasn't much of a singer but once was enough as far as getting shocked).
4. Learn existing harmony parts. If you have the opportunity to sing in a choir, you will learn a specific harmony part to sing against the melody (unless your part actually is the melody). This is a great way to experience how singing harmony is supposed to feel, and develop the independence to stick to your part even when someone else is singing a different part.
Also, seek out the harmony parts in the music you listen to. You might start with call-and-response type songs (if you're not Gladys Knight, you're a Pip - can you pick out your part?) and then try out some closer harmonies where two or more parts are moving together in the same rhythm. If it's not fun, you're doing it wrong - pick stuff you really like.
5. Improvise harmony parts where none exist. This is different from the approaches described above. There, you are just singing some notes and playing around. This is more like, Bono just pulled you onstage to sing with him on "One" and you better be able to come up with something.
I enjoy using this trick when the song is out of my range. If I were going to sing the melody it would be either too high or too low, but I can come up with a harmony part that fits (Jeff Tweedy, you ever need a backup singer, call me!).
I stopped at five, but there are many more approaches to harmonization. Let me know what's worked for you!