In my experience, it's not unusual to see a newbie grab the string with four fingers. However, for most folks, their little finger is so much shorter than their other three, that using it can lead to improper string hand alignment and/or torquing the string. I would agree with Greg, that you get your friend to start working with a three finger "hook"; either split or three under. If he's just really learning, and intends to shoot without a sight, I would encourage using three under as it gets the arrow closer to the eye which tends to make target alignment easier for a new shooter, IMHO. BTW, don't forget to determine your friend's dominant eye before he puts money out for a new bow.