How to handle beads during chanting?
Make sure your hands are carefully washed before beginning japa. Chant on the 108 beads by gently rolling them between the middle finger and the thumb. Never touch the beads with the index finger, which is generally used for a host of unpurified activities. Instead, keep that finger on the outside of the japa bag, placing it through the small enclosure in your bag which is made for that purpose. If you use your hands for anything other than chanting during the japa period, wash them again before coming back to your beads. Chanting on beads is especially helpful, for it engages the sense of touch in the meditative process and helps you concentrate even more on the sound of the mantra.
When chanting, begin with a bead next to the large 'head' bead. Chant around the beads, but never cross the 'head' bead. Rather, change direction on the beads, turning back the other way. Avoid having japa beads that are so small you can't be sure if you're chanting on one bead or two beads. Be careful not to skip beads, and don't skip ahead to the next bead while in the middle of the mantra. As you complete each round, pull down one of the small counter beads hanging on the outside of your bag, which are intended to help you keep track of the completed rounds.