You can use two simple acoustic blues techniques to give your blues guitar playing more variety. Alternating the texture creates an unexpected, less homogeneous sound. And combining open strings with fretted ones creates some unusual results by enabling some notes to ring while others move melodically.
Alternation
Alternation refers to the practice of playing the melody and bass parts one at a time, in an alternating fashion, instead of at the same time. Rather than having the thumb constantly play bass notes while the fingers simultaneously play melody notes, you can sometimes play just melody notes or just bass notes. This technique not only adds variety to the music’s texture, but it also enables you to play some cooler-sounding, more difficult, trickier licks that may otherwise be impossible.
This example shows a phrase that begins with only the melody (which you play in double-stops, a common acoustic blues technique) and ends with only bass (playing a boogie groove). You can see how the bass part — instead of playing merely quarter notes on the low roots — becomes more elaborate if you don’t need to worry about melody notes.
An effective and fancy little trick is to play an actual bass lick (that is, a bass melody instead of just a boogie figure) in an alternation scheme. The following example begins like the preceding example. That’s the melody’s turn in the alternation scheme. Then, in bar 2, the bass part takes its turn, so you can go to town with an exciting bass lick. Typically, these bass licks use notes of the E pentatonic minor (or E blues) scale with some major thirds (on the fourth fret of the 6th string) and major sixths (on the fourth fret of the 5th string) thrown in.
Open-string/fretted-string combinations
Another important acoustic-blues guitar technique is alternating between an open string and a fretted note (on an adjacent string) that’s the same pitch or a nearby pitch. You usually play this technique on the treble strings, but you can play it in the bass part as well.
In this example, you play the first high E on the 2nd string (a fretted note); next, you play the E on the 1st string (an open note) and then you play it back on the 2nd string again. The open E then recurs after you play some nearby notes on the 2nd string. Then the same idea occurs with the Bs on the fretted 3rd and open 2nd strings. Measure 2 (with the bass part playing alone) illustrates the same idea in a bass-part setting. On beats 3 and 4, the open D on the 4th string alternates with the 5th-string D and nearby notes.
