To play fingerpicking Blues, it is essential to be able to play notes simultaneously with the thumb (P) and one or more of the fingers. To begin with, the easiest way of developing this technique is to practice it with open strings, as demonstrated in the following example. It may take some time before you develop good control of this technique. Move on through the book, but be sure to spend a few minutes each day with this exercise. In time, it will become automatic and you will be totally free to concentrate on the music.
This traditional beginners piano piece is excellent for practicing thumb and fingers together on the guitar.