The simple addition of basic guitar nuances such as hammer ons and vibrato, applied to a rather pedestrian melody, can add an element of uncertainty.
By delaying or rushing certain figures and phrases within our solo can push and pull the beat adding instability; a common melodic blues guitar tool.
Dynamics, in terms of volume (using both pick attack and adjustment to the volume pot) are a powerful method for creating expectation - with quieter passages - and the louder portions of a lick give balance.
The addition of slides to our melody, particularly to cut phrases short or add colour to our licks provide more tension possibilities. Sliding out of your final phrase communicates a certain completion and finality.
Arpeggios: these give a more delicate and ‘pretty’ air when compared to the more earthy and soulful feel generated by more guitaristic blues and pentatonic scale based licks.
Blending traditional blues scale and pentatonic repertoire with phrases which incorporate diatonic (7 note scales) tones such as 9ths, again sets up the feeling of expectation vs stability.
Outside tones, from the melodic minor scale modes for example, when placed immediately before a chord change or musical figure serves to add extra tension and resolution when our new chord or section arrives.