Here we want to take your blues guitar skills to the first advanced level the easy way. The goal is that you can play along with the chords. In this case it's a standard blues form in G with quickchange :

G7 / C7 / G7 / G7 /
C7 / C7 / G7 / G7 /
D7 / C7 / G7 / D7

Here you can download the files associated to this tutorial :

Thank you Hanspeter,
what you mentioned about 7th chords (7:30) is a cool rule of thumb!
I knew that level V in the cadence should usually be a 7th chord, but I didn't know exactly why.

Gemini replied to my question with this:
The "rule of thumb" you're describing is not a hard-and-fast rule, but it is a very common and powerful technique. The practice of using a dominant 7th chord (V7) before a chord change is fundamental to what's known as a V-I cadence.

Here's why it works and why it's so widely used:

• Tension and Resolution: A dominant 7th chord is inherently unstable and creates a strong sense of tension. The root of the chord is the fifth degree of the scale you are moving to (the "tonic"). The 7th of the chord creates a tritone with the 3rd, which is a very unstable interval. This tension creates a strong pull or need to resolve to the stable, tonic chord (the "I").

• Creating Forward Motion: By placing a dominant 7th chord right before a new chord, you are essentially "setting up" the next chord. It creates a feeling of forward motion and expectation, making the chord change feel purposeful and satisfying.

• Defining the Key: This V-I relationship is the backbone of traditional harmony and is how we define a key. By playing a G7 chord, for example, the listener immediately anticipates a C major chord, which firmly establishes C as the tonic.

Thanks and best regards, Roland