If you have been playing for a while you will have some phrases that ricochet around your brain under the pressure of having to volley! 'Don't swing at the ball.' 'Out in front!' 'Just like a punch!' But let's take a different approach! Let's look at real game situations. How you hit the ball, how hard, your target area, could be different in each case. We will take singles situations first.
FACING A BACKHAND PASSING SHOT (hit by a right-hander from the backhand corner).
You have moved in close to the net, either by choice, or forced in by a short ball, and have hit your approach shot to your opponent's backhand corner. You are positioned to the right of the centre line to be equidistant from all their choices. They have 4 basic options. They could try a down the lie passing shot. They could attempt a hard cross court pass. Their third option could be a slow dipping short angled shot, or they could go for a lob over your head.
Hard down the line attempt.
You have to be ready for a fast ball, fairly low over the net, wide enough so you have to move quickly to your right, for a forehand volley. The 'percentage' play is a blocked volley angled towards the other corner, hit with slight underspin for control. Probably no need to generate extra speed, and not enough time for a big swing. So, the recommended grip is a compromise. A grip that allows you to hit both forehand and backhand volleys. Called the Continental Grip. Lock the wrist by keeping the racket head relatively above the wrist. Very little backswing. Aim for a big target. Think of the cue words 'Lock & Block'!
Hard across court attempt
This time you are forced to hit a backhand volley. As it is travelling across court, if you can take a step diagonally forward you have less distance to cover. The safest reply is to hit a 'stab' volley, just nudge it straight down the line, the shorter the better! Again, no need for, nor enough time for a big swing. Just put your racket head on the ball, keep the wrist firm with a continental grip. Let it bounce off, short. Most likely a point winner for you!
Slow, low angled cross court
A more defensive play from the baseliner is the slowly hit cross court angled shot. The intention here is to force you, the volleyer, to hit a defensive 'up' volley, to give the baseliner a second, and hopefully easier chance to force the pass.
In this situation your best reply is a slow 'up' volley down the line preferably deep. This backhand needs to be hit with a continental grip to impart some underspin for control. A very tough volley, but if played well, you will be in a better position for the next attempted pass! 'Up and Underspin'.
A lob
Your opponent may try to lob you. So you may be forced to hit an overhead smash if you can reach it. Yes, a smash is a volley! Good technique on the smash requires a different take-back than the serve, because you may have much less time than you think to get your racket ready into the 'cocked' position.
'Swingers' - those who take the racket back in a full swing like their service action - are more vulnerable to lower, faster lobs than 'Saluters' who have a fast take-back - just up past the forehead into the 'cocked' ready position. Move back sideways with crossover steps to be behind the ball. That makes it easier to hit aggressively, with the ball contact in front. Aim for a big target, best into the open court to the forehand of your opponent. Not too close to the lines. There are no bonus points to be won for a risky, flashy shot!
FACING A FOREHAND PASSING SHOT
(hit by a right-hander from the forehand corner)
Hard down the line attempted pass
This time you have to react with a backhand volley. The ball will be coming fast and low over the net. So the same 'lock and block' technique as you did on your forehand side for the down the line pass. Again, block the ball across court without trying to add any speed. If the pass attempt is a bit slower and higher you may have to take a bigger swing to take full advantage.
Hard and fast across court attempt
Again, a leaping 'stab' at the ball maybe all that is required to win the point with a short straight, down the line volley. Continental grip. Small compact stroke. If you can move diagonally forward you will have less distance to cover.
Slow, low angled cross court
The slow,dipping angled shot requires a well controlled 'up' defensive volley, best hit slowly but deep to their backhand. Their intention again is the '2 shot pass' tactic, to make you hit a defensive volley to give them an easier second chance to beat you at the net! Continental grip, an open racket face to impart underspin for control.
A lob
If they choose a lob, their best option is to hit it down the line over you ( as a right-hander) on the backhand side. It's lower trajectory might force you to hit a high backhand volley or backhand smash.
Let's look at possibly the most difficult volley. It requires great timing, and a loose, low grip. Badminton players are very familiar with this shot, and use a 'quick flick' to get enough racket head speed to hit quite aggressively.
Best hit across court to the open backhand corner, but prepare yourself for the next volley, as it is not likely your volley will be an outright winner! If the down the line lob is reachable as a regular overhead, then the best target area is angled off towards the side 'T' rather than hit hard and deep. And possibly less risky.