A lot of people think that sight-reading on the guitar is a difficult if not impossible task. It certainly is more difficult than for other instruments but it is possible and you can learn how.
The key is to get good at positional playing, and of course to follow the usual guidelines that players of other instruments follow.
This guitar lesson outlines the thought process I go through when I sight-read a new piece of music that's written in standard notation.
First things First
Check the obvious things. It's surprising how easy it is to forget to do this.
Time signature -- we get so used to playing in 4/4 time that we can mistakenly assume a piece is in 4/4 without looking. But there are many songs in 3/4, and occasionally other time signatures. So don't forget to check.
Tempo markings -- check if there is an indication as to what the tempo of the song might be. There might be an indication of the beats-per-minute for each quarter note, or there may be something more loosely guiding you to the tempo, like “fast,” or “moderato” etc.
Key Signature -- Check the key signature and then scan the first few bars of music to get an idea if the song is in the minor key or the major key.
Funny Stuff -- Scan through the page to look for any “funny stuff.” That's what I call accidentals, repeats, key changes, or any other markings that you will need to watch out for. Scanning ahead just puts them into the back of your mind and doing so makes it much easier to play. You won't be caught off guard.
The key to effective sight reading on the guitar is to get good at positional playing, and choosing an appropriate position to start in that will either cover you for the entire piece, or make it easy to shift into other positions to reach notes in higher or lower octaves.
TIP: If you are not already familiar with the five standard positions of the major scale, you should study these first. Choose just one position each week. Memorize the shape, noting where the roots are. Play the shape up and down three times a day. Always start on the root note and end on the root note (which is not necessarily the lowest note in the shape). That way your ears will get accustomed to the sound of the major scale.
Choosing a position
This is the process my brain goes through in deciding which position to use before I begin to read a new song:
Key -- The key signature will guide me as to where my five positions of the major scale will be. So if you haven't already done so, check the key signature!
Octaves -- Scan the first page of music and notice what octaves the music is in, or mostly in.
Positions -- Choose a position that will cover most or all of the music. If the music covers more octaves than any one position on the guitar will cover, then choose a position that will make it fairly easy to shift positions, or reach into the next position, so that you can play the music comfortably without having to shift your hand around too much.
Additional tips while reading
Focus hard -- As soon as you lose focus, you'll start making mistakes. Let your eye follow the music carefully and don't let it wander or "glaze over."
Read Ahead -- If you are quick at recognizing the notes on the staff, you can “read ahead” of what you are actually playing. Your eyes should be a few notes ahead of what you are actually playing on the guitar.
Notice intervals -- The more you read music, the more you will notice long sequences that run scale-wise. These are easy because your left hand should already have memorized the common scale shapes on the guitar, and it can simply run up or down that shape. In time, your eyes may be able to identify arpeggios, or snippets of arpeggios, major 3rds, 5ths etc, at a glance.
Have a look at this short piece of music:
Did you note the key signature and time signatures? It's a fairly easy one since it's in C major and it's 4/4 time.
The next thing I would do is scan ahead to check what octaves the music covers. As I scan the music, the image of the C major scale in 2nd position pops up in my head.
In other words, this position of C major on the guitar will cover us for all five bars. So we're good to go!
This piece is in the key of Bb major:
As I scan through the bars of music, I can see that there are more than two octaves covered in the piece. Since I don't have any one position on the guitar that can cover three octaves, I know that I will have shift positions at some point.
The majority of the notes will fit into this position of Bb Major:
... and I can just reach up into the next position to get those notes that are in the next position above.
When I scan the music I also notice that there is an accidental in bar 2. I'll remember that when I get to it so it won't catch me by surprise.
Following these steps will make you much faster and more confident at sight-reading on the guitar. Try picking any piece of music to practice sight reading every day.
The books I use with my guitar students who want to learn sight-reading are the old Berklee Press books by William Leavitt called A Modern Method for Guitar. They're not perfect books, but they're the best ones I've found so far.
What I like about these books is that the music you sight read is not recognizable, so you can't guess by ear what the next note will be, like you would if you recognized the melody. They also start out quite easy, but get hard pretty fast, and they do an okay job of demonstrating positional playing, as I've explained above.