The right hand's for tone, the left for notes.Experiment with different tones and dynamics. If you're on acou try picking in different parts of the strings, near the bridge for 'cold' trebly sounds, near the fretboard for warm sounds. If on electric try using the pickup selector in different positions or use the tone knob like a wah-wah. Best of all there's the volume knob so you can swell the notes from zero cutting out the trebly atack of the note. This creates a soft warm sound that's brill with some delay. Bear in mind that palm muting's great too. If you alternate that sort of thing up with pinch harmonics the tone difference adds something cool to your playing.

Get a good vibrato. There's the across fretboard type (AKA butterfly vibrato) with a wide sound to it and the along the strings classical type (which modulates pitch up and down instead of just up and is narrower). Takes heaps and heaps of practice and I'm still not there but it's getting better.

Try some new scales. If you're bored of the ones you know it's time to try something new.

Try pinch harmonics, they're a great way of jumping in pitch without having to move your fretting hand so far.

Add chords to your soloing, it gives it some rhythmic structure in a way that accentuating single notes just cannot do.