A good way to put padding between your glass table top and its frame is to get some glass table pads. These rubber pads make sure the glass surface does not move, and it keeps the table from making noise if the glass does not sit perfectly well on the frame.
Glass table pads:
Glass table pads pictured: 12pc Stick-on Clear Silicon Non-Skid Pads Self-Adhesive by HK
Since we are dealing with glass, a good idea is to get pads that are transparent. This way they will hardly be visible at all.