An interesting soloing technique used in jazz is playing 'outside', which basically means you play lines that are not related to the key you are in. For example, if you are playing in the key of Cmi and your solo uses notes from the Bmi scale, you are essentially playing 'outside'. This technique is usually for advanced players because it is challenging to make it work, however, it is a lot of fun and adds an extra dimension to your playing.

I've included an example below to get you started where you have a Cmi11 chord vamp with the pentatonic scale stepping above and below the actual tonality. In example 2, the V chord is being implied in the melody against the i chord causing interesting melodic and harmonic friction. This really heightens tension and makes the resolution back into the tonality even more significant because of the extended period of dissonance.

For more on 'outside' playing, be sure to check out the videos below. In each video, I explore the great exponents of 'outside' playing through discussion and by playing examples on the guitar.