cutting glass tiles with a miter saw
dont try to cut glass on a mitre saw.  the blade goes too fast and other than the glass particles destroying every moving part of your saw (including the teeth), you are essentially trying to detonate a hand grenade this way

the key to cutting glass is the following:

1)  make sure you are using a sharp scoring wheel.  if you cant remember the last time you rotated or replaced the wheel, its time to do so.

2)  use light oil on your cut.  just dribble a little line of it down where your cut is going to go.

3)  use a straight edge.  just clamp (gently) or double sided tape a straight edge to the glass plate.  remember when positioning it to take into account offset for the thickness of the tool

4)  score once and once only.  slow, with even pressure is the key, from one edge all the way to the other

5)  put a thin wood or metal bar under the glass and push down on both sides to break the piece off.  dont try to hold one side over a table edge or something and snap down.  this technique is only for professional glaziers

6)  debur the edge with a diamond cloth, rock cloth or a diamond flat file.  dont try to use sandpaper or a sanding block.  

7)  above all else, wear good quality work gloves or cut proof gloves and a faceshield or good safety glasses