If you haven’t yet begun singing with the songs that you are learning, it’s time! Singing will help you to develop pitch sense and will teach you where the melody notes occur in relation to the beat. By singing in each practice session you will vastly increase your comprehension of music in general.
Choose a song that you have been working on and make a recording of the guitar accompaniment, using either a picking or strumming pattern. Don’t worry about the sound quality of the recording device – just make sure the pitch and rhythm remain stable.
Turn on your metronome and record at least one measure of lead-in clicks, followed by at least one measure of accompaniment before the melody (the singing part) begins. (If you are plugging straight in to your recording device, you can establish the pulse by tapping your guitar strings on the beat for one measure before you begin to play.) This lead-in accompaniment will allow you to come in at the appropriate time when you listen back and will give you a clue to your starting pitch. Record the song five or six times in a row, without pause.
After you have a satisfactory recording, play it back and sing along with the sound of your guitar. Get comfortable with the sound of your own voice and guitar and practice until it feels natural and sounds correct.
If you are not certain that you are singing on pitch (or you are certain that you are not!), you will benefit from having written music for the song you are learning. Find the first note (starting pitch) of the melody and play it on your guitar. Match your voice to that pitch before strumming the first chord.
You can also use the written music to help you determine the direction of the melody notes and the distance from one note to the next. Be picky about every note!
Once you pick up your guitar, you may find that at times you have trouble singing in time to your accompaniment. If that is the case, go back and work with your recording again. After you perfect your performance with the recording, begin using your right hand to clap the beat while you listen and sing. When you put it all together on your guitar, it should seem much easier!