Here's a chord chart for "I Got Stripes," originally written out for my student Wesley, the biggest Cash fan I know. Check out his great strumming in his Coffee Shop Jam performance. Part of what makes that groove sound so good is that he's accenting the 2nd and 4th beats of the measure, called the "backbeat." These are the beats the drummer normally plays on the snare drum. When you're lacking a drummer, and you really want your strumming to chug with momentum, accent the backbeat.
This is a tough strumming skill for beginners to learn. Wesley's ability to do it while strumming at lightspeed is pretty incredible.