Connecting guitar chords with single note runs and fills is one of the best ways to spice up a chord progression. This technique is widely used in all forms of guitar music, from classical to rock 'n' roll and everything in between. However, it can be quite confusing for a novice to know which notes to play when crafting a fill or a run. But guitarists only need a basic understanding of music theory to learn how to use runs and fills to connect chords.
Brush up on your basic music theory. Be able to identify the key of the chord progression and know how to play basic major and minor scales in order to connect chords using fills and runs.
Play the chord progression until you are completely comfortable with it. Use a metronome to keep steady time.
Connect two chords using bass-note runs by starting on the root note of the first chord and walking up or down the scale until you reach the root note of the next chord. The duration of each note will depend on the duration of each chord and your own personal preference. Exactly when you start the run will also depend on your preference.
Experiment with different scalular tones instead of strictly ascending or descending the scale to connect chords. Also experiment with starting on or ending with chord tones other than the root note. At first, stay within the key of the chord progression. Once you become comfortable working with bass runs, experiment with chromatic tones to connect chords.
Add high fills between chords by playing lead licks in the key of the chord progression. Experiment with licks you already know before attempting to craft new ones. Ideally, these licks should end on a note that leads into the next chord, such as the seventh, third or fifth, but if the fill sounds good, use it.
Keeping correct time is very important when adding fills and runs to guitar chord progressions. Your fills and runs will sound bad if they are out of time, even if they are spectacularly flashy.