A glass shop or hardware store can make most cuts for you, but it pays to learn how to cut glass yourself if you are doing an art project or replacing your own window panes. It's an easy process provided you have the correct tools and know the proper technique.
Before cutting the glass, you need a proper glass scoring and breakaway mat to cover your work surface, and a shop brush for cleaning all of the broken glass particles. Protective eyewear is also a must when working with glass.
A glass cutter will score (cut) glass and are available in a variety of styles. From a pistol style to a pencil style cutter, what matters most is you are comfortable with your grip on the cutter and then practise, practise, practise.
Check out the video above for a great tutorial for scoring glass using these tools.
How To Cut Glass - The Basics [Delphi Glass Creativity Center]