When you have the welcome situation of meeting a volley well above the top of the net, you can hit it straight toward the target on your opponent's court, whether flat or with backspin, because there's nothing in your way. If you have to meet the ball well below the top of the net, you will probably realize that you must tilt your string bed to make the ball rise and apply backspin to keep its bounce low so that your opponent can't tee off on it. When the ball is just slightly above the top of the net, though, a lot of players get into trouble, usually by trying to hit the ball straight into the opponent's court as they would if the ball were higher. Most often, this results in hitting the ball into the net. From a normal volleying depth, balls that aren't at least 18 inches or so above the net must usually be hit as if they were below the net.
Any one-handed backhand grip that works well for other backhand volleys should work well for this volley, too. Two-handed volleys have many limitations, and difficulty hitting this shot two-handed might add to your motivation to switch to one hand. The Continental grip used here is at its most comfortable hitting this type of volley. A modified Eastern or full Eastern backhand grip will also work well.