I did go a bit cheap on my pliers set. They have worked pretty well for me for the past five years. No issues with them, but there are better ones out there for sure. I believe I got the set for $25 from Amazon. There are two pliers that you should get. Both serve different purposes. The first pliers that I will describe pretty much has one use while the second will have two different uses.
The running pliers will have a slight curve within the “teeth” of the plier and a set screw to set the thickness of the glass. Out will want to use these pliers to break a piece of glass that was cut with your glass cutter. You will want to place the piece of glass with the cut line entered in the teeth of the pliers with the set screw set to about the thickness of the glass (and set screw facing up). Lightly press the handle of the pliers together and that will break glass along the cut line. If it does not break at first back out the set screw and try again. I drew a center line on the top of my pliers to indicate center. Some pliers will have this line already there. Pretty straight forward and really only use for this pliers.
The second pliers that that ou will want to get is a grozer. This plier will have two jobs. The first one is to break the glass away from the final shape of a piece of cut glass. You will want to put the teeth of the pliers very close to the cut line lightly, but also enough force without crushing the glass, squeeze the pliers and then pull and slightly downwards with the pliers. Not to much downward force, to break the the glass away from the final piece it is more of a pulling motion. You will also want to make sure the the flat side of these pliers is on the top side of the glass. The curved side should be on the bottom. If you find that you are having trouble breaking the glass away, check the orientation of the pliers.
The second job of the grozer pliers it to nibble away at the glass to help define the shape of the piece. Taking as much glass off now will speed up the grinding process. When nibbling away at the piece of glass, either orientation works (for me), take small bites of the glass and apply more and more force to break small amounts of glass off.
Using these two pliers is all about practice and having the finesse and knowing how the glass will break. Much much practice and you will get the hang of it.