Layer citrus slices, fresh berries, or any other flavors that would taste good with the cocktail you are making, edible flowers are always nice. Remember the ice will eventually melt and the fruit will fall into the punch.
Fill half way with water and freeze (this is best done the night before to make sure it freezes completely).
When you are ready to serve, pop ring out of the pan by running hot water over the bottom until it comes out.
Notes
Make-ahead/Freezing Instructions: Give yourself at least 4 hours for the ice mold to freeze. It is best if done overnight.
Size: Make sure the mold will fit in your punch bowl before beginning. Set the mold you are using inside the punch bowl to make sure it will fit.