There's a ton of content out there on the proper way to hit the volley. In this brief post I'll go over the main points of how to hit a solid volley. There are two main kinds of volley: the mid court and the "at net". To play the net well you need both.
Here's some main points: keep your hands down and elbows bent slightly away from the body, in an athletic stance, with hands below the racquet, and hop up at contact of the player hitting the ball. The grip is continental for most players, but some players may not be able to hold a solid grip and require more grip changing to secure the racquet. The racquet head preparation is loaded at the height of the ball, keeping technique simple. Keep your elbows out a little. Set the racquet where the ball is going to arrive! This produces flat volleys! Keep your strings facing the target.
I found this tip by from Ryan (Two Minute Tennis). I think it's really good. I do however coach more backspin than he does (on the backhand volley) video.youtu.be/rpacFeUeioc?si=XCIzcIJm3MaiAjEe.
If you look at Stefan Edberg one of the best volleyers of all time (be patient, you'll have to see a few backhand volleys before getting to the forehand volley) you can see more slices being used on the bakchand wing. youtu.be/H89CnrqAruQ?si=0ivA7uOLxtaeHLBK
Take a look at Bob Bryan hitting some volleys. This was back in 2013 with his brother, Mike. Notice that there is little if any slice on the forehand volley. His elbows are not as bent as Ryan's two-minute video, but they are bent. He uses a bit of slice on the backhand volley but not a ton. youtu.be/kWLI14pN_QI?si=FSn8Cf75DVdYHXaV. Also, I like the way Bob is taking volley practice near the center of the court. This is great volley practice for doubles where most of the action is.
And finally, this is Leander Paes, the most amazing hands I've ever seen in doubles. His form is similar to Bob Bryan and Mike Bryan. youtu.be/o6qTdftF5LA?si=1Rt8fSzrChNt33SI
What about two-handed backhand shots? There's no better in the business than Chris Evert!