Watch the Building a New Groove online guitar lesson by Fareed Haque from Jazz Rock Workshop
I remember sitting with another comping genius, not Freddie Green, but Hiram Bullock (1955-2008) before taping Night Music with David Sanborn. If you want to see the show (and my legendary mullet) go to YouTube. Check it Out!
As he and I prepared, he revealed how he mutes strings and the almost the mad science quality of muting strings and strumming to get to the funky guitar parts we so love.
Mute top notes, mute bottom notes, use your left hand, your right hand, even your nose if needed to get the "spnk" of the strings (without all of the extra notes). All the while, keeping your rhythm, because music is not about notes, it's first about the rhythm.