Walking on a glacier needs some good rope discipline to keep you prepared at all times for a crevasse fall, the easiest way to visualise this is that rope should just touch the snow between each person. If there is more slack than this and someone falls in a crevasse the person on the surface will be shock loaded and will find it difficult to hold the fall. If the rope is tighter than this it will become very annoying to walk with.

In a heavily crevassed areas, lengthen the distance between each person and tighten the rope to make a fall easier to hold. Also consider tying overhand knots in the rope which would bite into the lip of a crevasse and make it easier to hold a fall. Three or four knots in a 12m section of rope, should do. The down side of this is that the knots make it much more difficult to set up a hauling system to rescue your partner.