when im sweeping my picking hand sort of follows my fretting hand in a down up direction but my picking hand is in slight contact with the strings so as to mute em..its hard to explain but its how i mute the strings also i roll my fretting hand over the the notes so they dont get a chance to ring out so i get that sweeping effect. A good way to practice is to just use ur pick hand and leave the fret hand off then just practice sweeping down the strings so that way u know if the notes are ringing out cause u wanted a muted effect oh and i dont hold the pick to tight so it goes in the direction im sweeping so if im sweeping down the pick sort of falls over the strings... but thats regular sweeping if thats what u are asking about ..