To make this even more effective try gently resting the right hand over the bridge while you play to slightly deaden or mute the sound - very rock and roll!

Once you've mastered doing a clean regular rhythm, try changing from G to A and the open E as in the intro to Since You've Been Gone:

Kelly Clarkson's Since You've Been Gone uses a popular guitar technique of playing 5ths on the lowest 2 strings of the guitar.