How to play the blues on guitar and sing the blues?

No, the blues scale is only rarely used in blues. Blues is a feeling and there are some basic formats often used. Listen to blues for a while and you will begin to see that the blues covers a lot of ground. "Crazy" is blues. So is "Sweet Home Chicago" I don't think the blues scale has a whole lot to do with it.

The blues has it's unique flavor due to the use of a minor third tone, a diminished fifth tone, and a dominant seventh tone. Whereas a major scale in the key of C would be C D E F G A B, the pentatonic (five tone) scale for a bluesy song in C would be C Eb F G Bb. The fifth tone in the key of C is the G note. For a bluesy sound you can throw in an F# note from time to time to give it some spice. Often this is done by bending the F tone up 1/2 step. To hear this effect, play the following phrase: C - Eb - F# - F - Eb. (again, bend the F to get the F# tone) The blues often take the form of a 12 bar progression which typically goes like this (each bar is 4 counts) : C - 1 bar ; F - 1 bar ; C - 2 bars ; F - 2 bars ; C - 2 bars ; G - 1 bar ; F - 1 bar ; C - 1 bar ; G - 1 bar Of course there are all the different kinds of chords you can use : 7th, 9th, 13th, augmented 9th, etc. And there are variations on the progressions. You'll just have to listen to see how the good players do it. Good luck.