Whilst giving a blowjob / hand job, one should NEVER neglect the balls. Neglecting the balls can be very dissatisfying for a male.
Man 1: "Man, she was the worst blowjob I've ever had"
Man 2: "Why's that?"
Man 1: "She neglected the balls dude..."
Man 2: "OOOOO, I feel for you brother. Never neglect the balls"