Your mission at the net is to contact the ball above the net height therefore being able to create angles and put the ball away. If your contact point is below the net height, angles become difficult and you have limited options.
This is where a lot of players get it wrong. If contacting below the net height you net to treat it as another approach shot, setting up for a high volley on the next. The best way to do this is play the ball deep DTL hoping to force a defensive lift from the opponent.
So to recap, if volleying below the net play deep DTL, and when you get a high volley contact put the ball away at a good angle, often crosscourt to finish the point.