A scale (Chords A7, D7, E7)
From The Cradle: Hoochie Coochie Man From The Cradle: Five long Years From The Cradle: Goin' Away Baby From The Cradle: Groaning The Blues
E scale (Chords E7, A7, B7)
Unplugged: Before You Accuse Me Unplugged: Hey, Hey Unplugged: Malted Milk From The Cradle: Blues Before Sunrise From The Cradle: How Long Blues From The Cradle: Blues Leave Me Alone From The Cradle: Sinner's Prayer From The Cradle: It Hurts Me Too From The Cradle: Driftin' Blues Breakers feat. EC: Ramblin' On My Mind
Another more detailed view showing bars and beats looks like:
1 2 3 4
| E7 / / / | E7 / / / | E7 / / / | E7 / / / |

5 6 7 8
| A7 / / / | A7 / / / | E7 / / / | E7 / / / |

9 10 11 12
| B7 / / / | A7 / / / | E7 / / / | / B7 / / |

This chord progression usually doesn't change during the whole song. Most Blues are played in 4/4 time, that means you have four quarter notes per bar. Slow Blues is often played in 12/8 time, that means twelve quavers ("eights notes") per bar.
The same in the key of A:
A7 - A7 - A7 - A7
D7 - D7 - A7 - A7
E7 - D7 - A7 - E7
E7 - A7 - E7 - E7
A7 - A7 - E7 - E7
B7 - A7 - E7 - B7
Most Blues start with an intro. Back in the old Blues days it was played in jukejoints and bars where it was quite loud. To get more attention and to make the audience hungry for the song one or a few bars where played loud without vocals, just a chord sequence or some notes ending on the V chord (B7 in our example). A simple intro can be achieved playing the chord sequence E - E7 - A - Am - E - B7 (audio example). For Malted Milk we use a typical robert Johnson intro, which can (like many other intros) be used as a turnaround, too:
E B7
Using the same notes we can also get some new turnarounds elsewhere on the fretboard - just to have some if we need one. A turnaround is very popular in Blues music, it's a riff or chord progression at the end of a section (for example the first 12 bars) leading to the next section (the next 12 bars). Usually it ends with the dominant 7th chord, B7 in this case. But it's easier to identify a turnaround by ear than to describe it using music theory.
I-----------------4-4---4-4---or this way-------------------2-2-----2----I
The turnaround is played at the end of the 12 bars to prepare for the next verse. Both intros and turnarounds often contain chromatic runs, that means going up or down in semitone steps (from one fret to the other is a semitone):




Blues in D MP3...so start this one on fret 10...

Blues Progression in D...Chords


Blues in D MP3


Blues in Bm Mp3...so start this scale on the 7th fret....

Blues Progrression in Bm...Chords


Blues in Bm MP3


Allman style..MP3 Below


Below Bending Blues

Bending Blues MP3

Below Push and Pull slow Blues

Push and pull slow blues MP3