i shave my pubes, also my balls.
for the balls, you have to stretch the skin and apply minimal shaving force so as not to cut its skin. it would also be a big help if at first you would do it with the flow of the pubes, then against it for a cleaner shave.
reason for shaving: looks good and feels cleaner
frequency: every two weeks or when the situation calls for one
tips: DONT EVER SCRATCH it!!! even when it gets very itchy. i suggest that you dry your private areas completely before wearing your underwear. also, during the first 2-3 days after shaving, it would help to wear shorts/pants that are a bit loose.