Guitar players who want to play solos need to learn several ways to play scales over chord progressions. 


Knowing the key and the chord relationships are critical for achieving success. The trick is to understand how to use several methods of key and chord relationships to select scales that will work the best when soloing...

Soloing Over a Key:
Soloing by "Key" is the easiest method of soloing because you treat the entire song as one key center. This is done by selecting the scale that fits with the entire key and then only play the notes of the associated scale.

Associated Keys and Scales:
Scales use the notes of the key signature and the chords are constructed from also using those same notes. For example, the "C Major scale" can be used to build all of the chords found in the key of "C Major."



Major Scales:
C Major scale and Chords for the key of C Major:



 
Minor Scales:
If we begin a Major scale off of the 6th degree, we create the "Relative Minor." In the key of "C Major" the 6th note is "A." Therefore, the "A Minor" scale is equivalent to the "C Major."

A Minor Chords for the key of A Minor:



PENTATONIC:
You can substitute the major or minor pentatonic scale for the major or minor 7-tone scale because all its notes are part of the same key.

8th Position "C Major" Pentatonic:


Now that you have your scales, you can play any note in that scale and it should sound good over any progression that is in the same key. The easiest way to do this is by using a known scale pattern. If you don’t know your scale patterns, use the pattern of the 8th position "C Major" scales shown above.



Soloing Better:
End your phrases on the root note at first. It will reinforce the key.

Listen for the notes that sound best over each chord.Search for the best notes.

Change positions when you play so you play low notes and high notes.

Use dynamics by varying the volume of your playing.

Use bends, slides, and vibrato to enhance your solos.

Soloing by key works well for beginners, but you will eventually want to use more sophisticated ideas. That is why it is also good to study soloing by chord.

Soloing Over a Chord
Keys rarely change within a song, but chords change often. The most interesting soloists change their soloing strategy based on the chord rather than the key.



Pentatonic Scales Targeting into Chords:
It is hard to go wrong with Pentatonic Scales. They limit themselves to 5 notes that work well over many different chords. The rule is to use Major pentatonic scales over major chords and minor pentatonic scales over minor chords.

 This works well for most chords. All you need to do is switch scales with the chord changes. For example, if the progression was Dm7 – G7 – Cmaj7, you could play D minor pentatonic, G major pentatonic, C major pentatonic. You just need to shift the scale and play any note in the scale.

Because pentatonic scales only have five notes, they can start to sound boring and repetitive. That is why we use other scales and the modes.

Major Scale and Minor Scale
Similar to soloing over a key, you can use the major and minor scales to solo over chords. The major scale can be used over major chords, and the minor scale can be used over minor chords. Both scales, however are considered modes using the names, Ionian and Aeolian respectively.



Modes
Modes are made for soloing over chords. Each mode is able to play over a specific set of chords. If the chord is dominant, like a G7 or G9, you’d want to play the Mixolydian mode. If it is a minor chord, you can play the dorian, phrygian, or aeolian mode.

As the chords get more complex, the mode choices go down. Use the chart below to select the best mode for each chord.

I	Major	Ionian (Major Scale)	Major, Major 7
II	Minor	Dorian	Minor, Minor 7
III	Minor	Phrygian	Minor, Minor 7
IV	Major	Lydian	Major, Major 7
V	Major	Mixolydian	Major, Dominant 7, Dominant 9
VI	Minor	Aeolian (Natural Minor Scale)	Minor, Minor 7
VII	Minor	Locrian	Diminished, Minor 7b5

Chord Tones
Some guitarists solo using chord tones. As the chord changes, you change the notes that you play. Arpeggio patterns are a great way to learn the chord tones.

Approach to Using Scales
Once you have a scale, mode, or chord arpeggio to use, there are a lot of techniques that you could start to apply.

Emphasize the root note of the current chord.

For modes, try playing every other note. This can work well to map out the chord tones.

Try to use voice leading into upcoming chords.

Before the next chord arrives, play a note that is a half step or a whole step away from the next chord’s root. This will help lead into the next chord. It takes some practice to master, but it sounds excellent.

What’s Next?
Soloing is mostly about knowing what notes to play. And, a lot of it is done through instinct. We can simplify the process by using full scales, pentatonics, and modes. But the best thing to do is to use backing track chord progressions and start practicing your improvisation with Jamtracks.