This technique is good not only for those who need help right off the bat but for doing forced reps when you CAN do full reps on your own. (fitstep.com)
The goal is to simply complete as many full reps as possible before your muscles fail. (sportstarsmag.com)
Make sure you're performing full reps; don't stop when your eyes are level with the bar, get your chin over it each time. (onnit.com)