Watch the Dynamics online guitar lesson by Mimi Fox from Graduated Solos
Classical musicians work constantly on dynamics ... how a particular section is played, and how this impacts the listener - very important!
Try playing softly in the beginning of a solo and increasing the volume as you progress or vice versa! Listen to the difference it makes.
Dynamics can create a lot of drama in your playing and don't be afraid of being dramatic because you think it's not "cool" - being "cool" at the expense of genuine emotion in your music is not cool at all, and consequently your solos will sound anemic and false.
Everyone knows that to be a musician you have to be a sensitive human being. Who are you fooling with the false "cool" bravado anyway!?