Candles are the most popular way to illuminate centerpieces. If you are using tall candles, they should be placed at the back of the centerpiece to keep them from falling over. If you are using shorter candles, place them at the sides of the centerpiece to give off more light. If you are using pillar candles, position them in the center to keep them from wobbling. A glow stick is the best way to light up centerpieces. A glow stick is a device that produces light through chemical reactions and actually glows in the dark. These devices work by inserting and then snapping a small glass tube with liquid into a hard plastic tube.