Loop on both ends of rope
I was taught that the loop can be very valuable--if for some reason you ever need more rope, you can quickly clip another bag on to the loop with a carabiner and you instantly have another 75' to work with. This can be especially critical in a live bait swim.
A good point was made earlier about pulling out some rope first. But it applies solely to relatively short throws-- make sure you throw the rope end first. If that misses, you can then throw the bag with 50-60' of rope still in it.
Someone also made a good point about having the swimmer turn around and put the rope over their shoulder. If you want them to go right, they put the rope over their left shoulder. This will dip their left shoulder and they should automatically ferry right. The same applies for rope over the right shoulder--they should automatically ferry left.